v20i082: dmake - dmake version 3.7, Patch02g/12

[Dennis Vadura]

Submitted-by: Dennis Vadura <dvadura at watdragon.waterloo.edu>
Posting-number: Volume 20, Issue 82
Archive-name: dmake/patch02g
Patch-To: dmake: Volume 19, Issue 22-58

#!/bin/sh
# this is dp2.06 (part 6 of a multipart archive)
# do not concatenate these parts, unpack them in order with /bin/sh
# file dm37p2 continued
#
if test ! -r _shar_seq_.tmp; then
	echo 'Please unpack part 1 first!'
	exit 1
fi
(read Scheck
 if test "$Scheck" != 6; then
	echo Please unpack part "$Scheck" next!
	exit 1
 else
	exit 0
 fi
) < _shar_seq_.tmp || exit 1
if test ! -f _shar_wnt_.tmp; then
	echo 'x - still skipping dm37p2'
else
echo 'x - continuing file dm37p2'
sed 's/^X//' << 'SHAR_EOF' >> 'dm37p2' &&
Xcommand line flag.
XIf a prerequisite name cannot be found in the environment
Xan error message is issued.
X\&.IMPORT accepts the .IGNORE attribute.  When given, it causes \fBdmake\fP
Xto ignore the above error.
XSee the MACROS section for a description of the processing of imported macro
Xvalues.
X.IP \fB.INCLUDE\fP 1.4i
XParse another makefile just as if it had been located at the point of the
X\&.INCLUDE in the current makefile.  The list of prerequisites gives the list of
Xmakefiles to try to read.  If the list contains multiple makefiles then they
Xare read in order from left to right.  The following search rules are used
Xwhen trying to locate the file.  If the filename is surrounded by " or just
Xby itself then it is searched for in the current directory.  If it is not
Xfound it is then searched for in each of the directories specified for the
X\&.INCLUDEDIRS special target.  If the file name is surrounded by < and >, (ie.
X<my_spiffy_new_makefile>) then it is searched for only in the directories
Xgiven by the .INCLUDEDIRS special target.  In both cases if the file name is a
Xfully qualified name starting at the root of the file system then it is only
Xsearched for once, and the .INCLUDEDIRS list is ignored.  .INCLUDE accepts
Xthe .IGNORE and .SETDIR attributes.  If .IGNORE attribute is given and the file
Xcannot be found then \fBdmake\fP continues processing,
Xotherwise an error message is generated.
XThe .SETDIR attribute causes
X.B dmake
Xto change directories to the specified directory prior to attempting the
Xinclude operation.
X.IP \fB.INCLUDEDIRS\fP 1.4i
XThe list of prerequisites specified for this target defines the set of
Xdirectories to search when trying to include a makefile.
X.IP \fB.KEEP_STATE\fP 1.4i
XThis special target is a synonym for the macro definition
X.sp
X\&\t.KEEP_STATE := _state.mk
X.sp
XIt's effect is to turn on STATE keeping and to define \fI_state.mk\fP
Xas the state file.
X.IP \fB.MAKEFILES\fP 1.4i
XThe list of prerequisites is the set of files to try to read as the default
Xmakefile.  By default this target is defined as: 
X.sp
X\t\&.MAKEFILES : makefile.mk Makefile makefile
X.sp
X.IP \fB.SOURCE\fP 1.4i
XThe prerequisite list of this target defines a set of directories to check
Xwhen trying to locate a target file name.  See the section on BINDING of
Xtargets for more information.
X.IP \fB.SOURCE.suff\fP 1.4i
XThe same as .SOURCE, except that the .SOURCE.suff list is searched first when
Xtrying to locate a file matching the a target whose name ends in the suffix
X\&.suff.
X.IP \fB.REMOVE\fP 1.4i
XThe recipe of this target is used whenever \fBdmake\fP needs to remove
Xintermediate targets that were made but do not need to be kept around.
XSuch targets result from the application of transitive closure on the
Xdependency graph.
X.PP
XIn addition to the special targets above,
Xseveral other forms of targets are recognized and are considered special,
Xtheir exact form and use is defined in the sections that follow.
X.SH "SPECIAL MACROS"
X.B dmake
Xdefines a number of special macros.  They are divided into three classes:
Xcontrol macros, run-time macros, and function macros.
XThe control macros are used by
X.B dmake
Xto configure its actions, and are the preferred method of doing so.
XIn the case when a control macro has the same function as a special 
Xtarget or attribute they share the same name as the special target or
Xattribute.
XThe run-time macros are defined when
X.B dmake
Xmakes targets and may be used by the user inside recipes.
XThe function macros provide higher level functions dealing with macro
Xexpansion and diversion file processing.
X.SH "CONTROL MACROS"
XTo use the control macros simply assign them a value just like any other
Xmacro.  The control macros are divided into three groups:
Xstring valued macros, character valued macros, and boolean valued macros.
X.PP
XThe following are all of the string valued macros.
XThis list is divided into two groups.  The first group gives the string
Xvalued macros that are defined internally and cannot be directly set by the
Xuser.
X.IP \fBDIRBRKSTR\fP 1.4i
XContains the string of chars used to terminate
Xthe name of a directory in a pathname.
XUnder UNIX its value is "/", under MSDOS its value is "/\e:".
X.IP \fBINCDEPTH\fP 1.4i
XThis macro's value is a string of digits representing
Xthe current depth of makefile inclusion.
XIn the first makefile level this value is zero.
X.IP \fBMFLAGS\fP 1.4i
XIs the list of flags
Xthat were given on the command line including a leading switch character.
XThe \-f flag is not included in this list.
X.IP \fBMAKECMD\fP 1.4i
XIs the name with which \fBdmake\fP was invoked.
X.IP \fBMAKEDIR\fP 1.4i
XIs the full path to the initial directory in which
X.B dmake
Xwas invoked.
X.IP \fBMAKEFILE\fP 1.4i
XContains the string "\-f \fImakefile\fP" where, \fImakefile\fP is the name
Xof initial user makefile that was first read.
X.IP \fBMAKEFLAGS\fP 1.4i
XIs the same as $(MFLAGS) but has no leading switch
Xcharacter. (ie. MFLAGS = \-$(MAKEFLAGS))
X.IP \fBMAKEMACROS\fP 1.4i
XContains the complete list of macro expressions that were specified on the
Xcommand line.
X.IP \fBMAKETARGETS\fP 1.4i
XContains the name(s) of the target(s), if any, that were
Xspecified on the command line.
X.IP \fBMAXPROCESSLIMIT\fP 1.4i
XIs a numeric string representing the maximum number of processes that 
X\fBdmake\fP can use when making targets using parallel mode.
X.IP \fBNULL\fP 1.4i
XIs permanently defined to be the NULL string.
XThis is useful when comparing a conditional expression to an NULL value.
X.IP \fBPWD\fP 1.4i
XIs the full path to the
Xcurrent directory in which make is executing.
X.IP \fBTMPFILE\fP 1.4i
XIs set to the name of the most recent temporary file opened by \fBdmake\fP.
XTemporary files are used for text diversions and for group recipe processing.
X.IP \fBTMD\fP 1.4i
XStands for "To Make Dir", and
Xis the path from the present directory (value of $(PWD)) to the directory
Xthat \fBdmake\fP was started up in (value of $(MAKEDIR)).
XThis macro is modified when .SETDIR attributes are processed.
X.IP \fBUSESHELL\fP 1.4i
XThe value of this macro is set to "yes" if the current recipe is forced to
Xuse a shell for its execution via the .USESHELL or '+' directives, its value
Xis "no" otherwise.
X.sp
X.PP
XThe second group of string valued macros control
X.B dmake
Xbehavior and may be set by the user.
X.IP \fB.NOTABS\fP 1.6i
XWhen set to non-NULL enables the use of spaces as well as <tabs> to begin
Xrecipe lines.
XBy default a non\-group recipe is terminated by a line without any leading
Xwhite\-space or by a line not beggining with a <tab> character.
XEnabling this mode modifies the first condition of
Xthe above termination rule to terminate a
Xnon\-group recipe with a line that contains only white\-space.
XThis mode does not effect the parsing of group recipes bracketed by [].
X.IP \fB.SETDIR\fP 1.6i
XIf this macro is assigned a value then \fBdmake\fP will
Xchange to the directory given by that value before making any targets.
X.IP \fBAUGMAKE\fP 1.6i
XIf set to a non NULL value will enable the transformation of special
Xmeta targets to support special AUGMAKE inferences (See the COMPATIBILITY
Xsection).
X.IP \fBDIRSEPSTR\fP 1.6i
XContains the string that is used to separate directory components when
Xpath names are constructed.  It is defined with a default value at startup.
X.IP \fBDIVFILE\fP 1.6i
XIs defined in the startup file and gives the name that should be returned for
Xthe diversion file name when used in
X$(mktmp ...) expansions, see the TEXT DIVERSION section for details.
X.IP \fB.KEEP_STATE\fP 1.6i
XAssigning this macro a value tells
X.B dmake
Xthe name of the state file to use and turns on the keeping of state
Xinformation for any targets that are brought up to date by the make.
X.IP \fBGROUPFLAGS\fP 1.6i
XThis macro gives the set of flags to pass to the shell when
Xinvoking it to execute a group recipe.  The value of the macro is the
Xlist of flags with a leading switch indicator.  (ie. `\-' under UNIX)
X.IP \fBGROUPSHELL\fP 1.6i
XThis macro defines the full
Xpath to the executable image to be used as the shell when
Xprocessing group recipes.  This macro must be defined if group recipes are
Xused.  It is assigned a default value in the startup makefile.  Under UNIX
Xthis value is /bin/sh.
X.IP \fBGROUPSUFFIX\fP 1.6i
XIf defined, this macro gives the string to use as a suffix
Xwhen creating group recipe files to be handed to the command interpreter.
XFor example, if it is defined as .sh, then all
Xtemporary files created by \fBdmake\fP will end in the suffix .sh.
XUnder MSDOS if you are using command.com as your GROUPSHELL, then this suffix
Xmust be set to .bat in order for group recipes to function correctly.
XThe setting of GROUPSUFFIX and GROUPSHELL is done automatically for
Xcommand.com in the startup.mk files.
X.IP \fBMAKE\fP 1.6i
XIs defined in the startup file by default.
XThe string $(MAKE) is recognized when
Xusing the \-n option for single line recipes.  Initially this macro is defined
Xto have the value "$(MAKECMD) $(MFLAGS)".
X.IP \fBMAKESTARTUP\fP 1.6i
XThis macro defines the full path to the initial startup
Xmakefile.  Use the \fB\-V\fP command line option to discover its initial
Xvalue.
X.IP \fBMAXLINELENGTH\fP 1.6i
XThis macro defines the maximum size of a single line of
Xmakefile input text.  The size is specified as a number, the default value
Xis defined internally and is shown via the \fB\-V\fP option.
XA buffer of this size plus 2 is allocated for reading makefile text.  The
Xbuffer is freed before any targets are made, thereby allowing files containing
Xlong input lines to be processed without consuming memory during the actual
Xmake.
X.IP \fBMAXPROCESS\fP 1.6i
XSpecify the maximum number of child processes to use when making targets.
XThe default value of this macro is "1" and its value cannot exceed the value
Xof the macro MAXPROCESSLIMIT.  Setting the value of MAXPROCESS on the command
Xline or in the makefile is equivalent to supplying a corresponding value to
Xthe -P flag on the command line.
X.IP \fBPREP\fP 1.6i
XThis macro defines the number of iterations to be expanded
Xautomatically when processing % rule definitions of the form:
X.sp
X% : %.suff
X.sp
XSee the sections on PERCENT(%) RULES for details on how PREP is used.
X.IP \fBSHELL\fP 1.6i
XThis macro defines the full path to the executable
Ximage to be used as the shell when
Xprocessing single line recipes.  This macro must be defined if recipes
Xrequiring the shell for execution are to be used.
XIt is assigned a default value in the startup makefile.
XUnder UNIX this value is /bin/sh.
X.IP \fBSHELLFLAGS\fP 1.6i
XThis macro gives the set of flags to pass to the shell when
Xinvoking it to execute a single line recipe.  The value of the macro is the
Xlist of flags with a leading switch indicator.  (ie. `\-' under UNIX)
X.IP \fBSHELLMETAS\fP 1.6i
XEach time
X.B dmake
Xexecutes a single recipe line (not a group recipe) the line is
Xsearched for any occurrence of a character defined in the value of SHELLMETAS.
XIf such a character is found the recipe line is defined to require a shell
Xto ensure its correct execution.  In such instances
Xa shell is used to invoke the recipe line.
XIf no match is found the recipe line is executed without the use of a shell.
X.sp
X.PP
XThere is only one character valued macro defined by \fBdmake\fP:
X\fBSWITCHAR\fP contains the switch character used
Xto introduce options on command lines.  For UNIX its value is `\-', and for
XMSDOS its value may be `/' or `\-'.
XThe macro is internally defined and is not user setable.
XThe MSDOS version of \fBdmake\fP attempts to first extract SWITCHAR from an
Xenvironment variable of the same name.  If that fails it then attempts to
Xuse the undocumented getswitchar system call, and returns the result of
Xthat.  Under MSDOS version 4.0 you must set the value of the environment
Xmacro SWITCHAR to '/' to obtain predictable behavior.
X.PP
XAll boolean macros currently understood by 
X.B dmake
Xcorrespond directly to the previously defined attributes.
XThese macros provide
Xa second way to apply global attributes, and represent the
Xpreferred method of doing so.  They are used by assigning them a
Xvalue.  If the value is not a NULL string then the boolean condition
Xis set to on.
XIf the value is a NULL string then the condition is set to off.
XThere are five conditions defined and they correspond directly to the
Xattributes of the same name.  Their meanings are defined in the ATTRIBUTES
Xsection above.
XThe macros are:
X\&\fB.EPILOG\fP,
X\&\fB.IGNORE\fP,
X\&\fB.MKSARGS\fP,
X\&\fB.NOINFER\fP,
X\&\fB.PRECIOUS\fP,
X\&\fB.PROLOG\fP,
X\&\fB.SEQUENTIAL\fP,
X\&\fB.SILENT\fP,
X\&\fB.SWAP\fP, and
X\&\fB.USESHELL\fP.
XAssigning any of these a non NULL value will globally set
Xthe corresponding attribute to on.
X.SH "RUN_TIME MACROS"
XThese macros are defined
Xwhen \fBdmake\fP is making targets, and may take on different values for each
Xtarget.  \fB$@\fP is defined to be the full target name, \fB$?\fP is the
Xlist of all out of date prerequisites, \fB$&\fP is the list of all
Xprerequisites, \fB$>\fP is the name of the library if the current target is a
Xlibrary member, and
X\fB$<\fP is the list of prerequisites specified in the current rule.
XIf the current target had a recipe inferred then \fB$<\fP is the name of the
Xinferred prerequisite even if the target had a list of prerequisites supplied
Xusing an explicit rule that did not provide a recipe.  In such situations
X\fB$&\fP gives the full list of prerequisites.
X.PP
X\fB$*\fP is defined as
X\fB$(@:db)\fP when making targets with explicit recipes and is defined as the
Xvalue of % when making targets whose recipe is the result of an inference.
XIn the first case \fB$*\fP is the target name with no suffix,
Xand in the second case, is the value of the matched % pattern from
Xthe associated %-rule.
X\fB$^\fP expands to the set of out of date prerequisites taken from the
Xcurrent value of \fB$<\fP.
XIn addition to these,
X\fB$$\fP expands to $, \fB{{\fP expands to {, \fB}}\fP expands to }, and the
Xstrings \fB<+\fP and \fB+>\fP are recognized
Xas respectively starting and terminating a text diversion when they appear
Xliterally together in the same input line.
X.PP
XThe difference between $? and $^ can best be illustrated by an example,
Xconsider:
X.RS
X.sp
X.nf
Xfred.out : joe amy hello
X\trules for making fred
XX
Xfred.out : my.c your.h his.h her.h	  # more prerequisites
X.fi
X.sp
X.RE
XAssume joe, amy, and my.c are newer then fred.out.  When
X.B dmake
Xexecutes the recipe for making fred.out the values of the following macros
Xwill be:
X.RS
X.sp
X.nf
X.Is "$@ "
X.Ii "$@"
X--> fred.out
X.Ii "$*"
X--> fred
X.Ii "$?"
X--> joe amy my.c  # note the difference between $? and $^
X.Ii "$^"
X--> joe amy
X.Ii "$<"
X--> joe amy hello
X.Ii "$&"
X--> joe amy hello my.c your.h his.h her.h
X.fi
X.sp
X.RE
X.SH "FUNCTION MACROS"
X.B dmake
Xsupports a full set of functional macros.  One of these, the $(mktmp ...)
Xmacro, is discussed in detail in the TEXT DIVERSION section and is not
Xcovered here.
X.RS
X.sp
X.IP "$(\fBnull\fP,\fItext\fP \fBtrue\fP \fBfalse\fP)"
Xexpands the value of
X.I text.
XIf it is NULL then the macro returns the value of the expansion of \fBtrue\fP
Xand the expansion of \fBfalse\fP otherwise.  The terms \fBtrue\fP, and
X\fBfalse\fP must be strings containing no white\-space.
X.IP "$(\fB!null\fP,\fItext\fP \fBtrue\fP \fBfalse\fP)"
XBehaves identically to the previous macro except that the 
X.B true
Xstring is chosen if the expansion of
X.I text
Xis not NULL.
X.IP "$(\fBeq\fP,\fItext_a\fP,\fItext_b\fP \fBtrue\fP \fBfalse\fP)"
Xexpands
X.I text_a
Xand
X.I text_b
Xand compares their results.  If equal it returns the result of the expansion
Xof the 
X.B true
Xterm, otherwise it returns the expansion of the
X.B false
Xterm.
X.IP "$(\fB!eq\fP,\fItext_a\fP,\fItext_b\fP \fBtrue\fP \fBfalse\fP)"
XBehaves identically to the previous macro except that the 
X.B true
Xstring is chosen if the expansions of the two strings are not equal
X.IP "$(\fBshell\fP \fBcommand\fP)"
XRuns \fIcommand\fP as if it were part of a recipe and returns,
Xseparated by a single space, all the non-white
Xspace terms written to stdout by the command.
XFor example:
X.RS
X.RS
X.sp
X$(shell ls *.c)
X.sp
X.RE
Xwill return \fI"a.c b.c c.c d.c"\fP if the files exist in the current
Xdirectory.  The recipe modification flags \fB[+@%\-]\fP are honored if they
Xappear as the first characters in the command.  For example:
X.RS
X.sp
X$(shell +ls *.c)
X.sp
X.RE
Xwill run the command using the current shell.
X.RE
X.IP "$(\fBsort\fP \fBlist\fP)"
XWill take all white\-space separated tokens in \fIlist\fP and will
Xreturn their sorted equivalent list.
X.IP "$(\fBstrip\fP \fBdata\fP)"
XWill replace all strings of white\-space in data by a single space.
X.IP "$(\fBsubst\fP,\fIpat\fP,\fIreplacement\fP \fBdata\fP)"
XWill search for \fIpat\fP in
X.B data
Xand will replace any occurrence of
X.I pat
Xwith the
X.I replacement
Xstring.
X.RS
XThe expansion
X.RS
X.sp
X$(subst,.o,.c $(OBJECTS))
X.sp
X.RE
Xis equivalent to:
X.RS
X.sp
X$(OBJECTS:s/.o/.c/)
X.sp
X.RE
X.RE
X.SH "DYNAMIC PREREQUISITES"
X.B dmake
Xlooks for prerequisites whose names contain macro expansions during target
Xprocessing.  Any such prerequisites are expanded and the result of the
Xexpansion is used as the prerequisite name.  As an example the line:
X.sp
X\tfred : $$@.c
X.sp
Xcauses the $$@ to be expanded when \fBdmake\fP is making fred, and it resolves
Xto the target \fIfred\fP.
XThis enables dynamic prerequisites to be generated.  The value
Xof @ may be modified by any of the valid macro modifiers.  So you can say for
Xexample:
X.sp
X\tfred.out : $$(@:b).c
X.sp
Xwhere the $$(@:b) expands to \fIfred\fP.
XNote the use of $$ instead of $ to indicate the dynamic expansion, this
Xis due to the fact that the rule line is expanded when it is initially parsed,
Xand $$ then returns $ which later triggers the dynamic prerequisite expansion.
XIf you really want a $ to be part of a prerequisite name you must use $$$$.
XDynamic macro expansion is performed in all user defined rules,
Xand the special targets .SOURCE*, and .INCLUDEDIRS.
X.SH "BINDING TARGETS"
XThis operation takes a target name and binds it to an existing file, if
Xpossible.
X.B dmake
Xmakes a distinction between the internal target name of a target and its
Xassociated external file name.
XThus it is possible for a target's internal name and its external
Xfile name to differ.
XTo perform the binding, the following set of rules is used.
XAssume that we are
Xtrying to bind a target whose name is of the form \fIX.suff\fP,
Xwhere \fI.suff\fP is the suffix and \fIX\fP is the stem portion
X(ie. that part which contains the directory and the basename).
X.B dmake
Xtakes this target name and performs a series of search operations that try to
Xfind a suitably named file in the external file system.
XThe search operation is user controlled
Xvia the settings of the various .SOURCE targets.
X.RS
X.IP 1.
XIf target has the .SYMBOL attribute set then look for it in the library.
XIf found, replace the target name with the library member name and continue
Xwith step 2.  If the name is not found then return.
X.IP 2.
XExtract the suffix portion (that following the `.') of the target name.
XIf the suffix is not null, look up the special target .SOURCE.<suff>
X(<suff> is the suffix).  
XIf the special target exists then search each directory given in
Xthe .SOURCE.<suff> prerequisite list for the target.
XIf the target's suffix was null (ie. \fI.suff\fP was empty) then 
Xperform the above search but use the special target .SOURCE.NULL instead.
XIf at any point a match is found then terminate the search.
XIf a directory in the prerequisite list is the special name `.NULL ' perform
Xa search for the full target name without prepending any directory portion
X(ie. prepend the NULL directory).
X(a default target of '.SOURCE : .NULL' is defined by \fBdmake\fP at startup,
Xand is user redefinable)
X.IP 3.
XThe search in step 2. failed.  Repeat the same search but this time
Xuse the special target .SOURCE.
X.IP 4.
XThe search in step 3. failed.
XIf the target has the library member attribute (.LIBMEMBER)
Xset then try to find the target in the library which was passed along
Xwith the .LIBMEMBER attribute (see the MAKING LIBRARIES section).
XThe bound file name assigned to a target which is successfully
Xlocated in a library is the same name that would be assigned had the search
Xfailed (see 5.).
X.IP 5.
XThe search failed.  Either the target was not found in any of the search
Xdirectories or no applicable .SOURCE special targets exist.
XIf applicable .SOURCE special targets exist, but the target was not found,
Xthen \fBdmake\fP assigns the first name searched as the bound file name.
XIf no applicable .SOURCE special targets exist,
Xthen the full original target name becomes the bound file name.
X.RE
X.PP
XThere is potential here for a lot of search operations.  The trick is to
Xdefine .SOURCE.x special targets with short search lists and leave .SOURCE
Xas short as possible.
XThe search algorithm has the following useful side effect.
XWhen a target having the .LIBMEMBER (library member) attribute is searched for,
Xit is first searched for as an ordinary file.
XWhen a number of library members require updating it is desirable to compile
Xall of them first and to update the library at the end in a single operation.
XIf one of the members does not compile and \fBdmake\fP stops, then
Xthe user may fix the error and make again.  \fBdmake\fP will not remake any
Xof the targets whose object files have already been generated as long as
Xnone of their prerequisite files have been modified as a result of the fix.
X.PP
XWhen defining .SOURCE and .SOURCE.x targets the construct
X.sp
X\t.SOURCE :
X.br
X\t.SOURCE : fred gery
X.sp
Xis equivalent to
X.sp
X\t.SOURCE :\- fred gery
X.PP
X\fBdmake\fP correctly handles the UNIX Make variable VPATH.  By definition VPATH
Xcontains a list of ':' separated directories to search when looking for a
Xtarget.  \fBdmake\fP maps VPATH to the following special rule:
X.sp
X\t.SOURCE :^ $(VPATH:s/:/ /)
X.sp
XWhich takes the value of VPATH and sets .SOURCE to the same set of directories
Xas specified in VPATH.
X.SH "PERCENT(%) RULES AND MAKING INFERENCES"
XWhen \fBdmake\fP makes a target, the target's set of prerequisites (if any)
Xmust exist and the target must have a recipe which \fBdmake\fP
Xcan use to make it.
XIf the makefile does not specify an explicit recipe for the target then
X.B dmake
Xuses special rules to try to infer a recipe which it can use
Xto make the target.  Previous versions of Make perform this task by using
Xrules that are defined by targets of the form .<suffix>.<suffix> and by
Xusing the .SUFFIXES list of suffixes.  The exact workings of this mechanism
Xwere sometimes difficult to understand and often limiting in their usefulness.
XInstead, \fBdmake\fP supports the concept of \fI%-meta\fP rules.  
XThe syntax and semantics of these rules differ from standard rule lines as
Xfollows:
X.sp
X.nf
X.RS
X\fI<%-target>\fP [\fI<attributes>\fP] \fI<ruleop>\fP [\fI<%-prerequisites>\fP] [;\fI<recipe>\fP]
X.RE
X.fi
X.sp
Xwhere \fI%-target\fP is a target containing exactly a single `%' sign,
X.I attributes
Xis a list (possibly empty) of attributes,
X.I ruleop
Xis the standard set of rule operators,
X.I "%-prerequisites"
X\&, if present, is a list of prerequisites containing zero or more `%' signs,
Xand
X.I recipe,
Xif present, is the first line of the recipe.
X.PP
XThe
X.I %-target
Xdefines a pattern against which a target whose recipe is
Xbeing inferred gets matched.  The pattern match goes as follows:  all chars are
Xmatched exactly from left to right up to but not including the % sign in the
Xpattern, % then matches the longest string from the actual target name
Xnot ending in
Xthe suffix given after the % sign in the pattern.
XConsider the following examples:
X.RS
X.sp
X.nf
X.Is "dir/%.c   "
X.Ii "%.c"
Xmatches fred.c but not joe.c.Z
X.Ii "dir/%.c"
Xmatches dir/fred.c but not dd/fred.c
X.Ii "fred/%"
Xmatches fred/joe.c but not f/joe.c
X.Ii "%"
Xmatches anything
X.fi
X.sp
X.RE
XIn each case the part of the target name that matched the % sign is retained
Xand is substituted for any % signs in the prerequisite list of the %-meta rule
Xwhen the rule is selected during inference and
X.B dmake
Xconstructs the new dependency.
XAs an example the following %-meta rules describe the following:
X.RS
X.sp
X%.c : %.y ; recipe...
X.sp
X.RE
Xdescribes how to make any file ending in .c if a corresponding file ending
Xin .y can be found.
X.RS
X.sp
Xfoo%.o : fee%.k ; recipe...
X.sp
X.RE
Xis used to describe how to make fooxxxx.o from feexxxx.k.
X.RS
X.sp
X%.a :; recipe...
X.sp
X.RE
Xdescribes how to make a file whose suffix is .a without inferring any
Xprerequisites.
X.RS
X.sp
X%.c : %.y yaccsrc/%.y ; recipe...
X.sp
X.RE
Xis a short form for the construct:
X.RS
X.sp
X%.c : %.y ; recipe...
X.br
X%.c : yaccsrc/%.y ; recipe...
X.sp
X.RE
Xie. It is possible to specify the same recipe for two %-rules by giving
Xmore than one prerequisite in the prerequisite list.
XA more interesting example is:
X.RS
X.sp
X% : RCS/%,v ; co $@
X.sp
X.RE
Xwhich describes how to take any target and check it out of
Xthe RCS directory if the corresponding file exists in the RCS directory.
XThe equivalent SCCS rule would be:
X.RS
X.sp
X% : s.% ; get $@
X.sp
X.RE
X.PP
XThe previous RCS example defines an infinite rule, because it says how to make
X.I anything
Xfrom RCS/%,v, and
X.I anything
Xalso includes RCS/fred.c,v.
XTo limit the size of the graph that results from such rules
X.B dmake
Xuses the macro variable PREP (stands for % repetition).  By default the value
Xof this variable is 0, which says that no repetitions of a %-rule are to be
Xgenerated.  If it is set to something greater than 0, then that many
Xrepetitions of any infinite %-rule are allowed.  If in the above
Xexample PREP was set to 1, then \fBdmake\fP would generate the dependency
Xgraph:
X.RS
X.sp
X% --> RCS/%,v --> RCS/RCS/%,v,v
X.sp
X.RE
XWhere each link is assigned the same recipe as the first link.
XPREP should be used only in special cases, since it may result in
Xa large increase in the number of possible prerequisites tested.
X.B dmake
Xfurther assumes that any target that has no suffix can be made from
Xa prerequisite that has at least one suffix.
X.PP
X.B dmake
Xsupports dynamic prerequisite generation for prerequisites of %-meta rules.
XThis is best illustrated by an example.  The RCS rule shown above can infer
Xhow to check out a file from a corresponding RCS file only if the target
Xis a simple file name with no directory information.  That is, the above rule
Xcan infer how to find \fIRCS/fred.c,v\fP from the target \fIfred.c\fP,
Xbut cannot infer how to find \fIsrcdir/RCS/fred.c,v\fP from \fIsrcdir/fred.c\fP
Xbecause the above rule will cause \fBdmake\fP to look for RCS/srcdir/fred.c,v;
Xwhich does not exist (assume that srcdir has its own RCS directory as is the
Xcommon case).
X.PP
XA more versatile formulation of the above RCS check out rule is the following:
X.RS
X.sp
X% :  $$(@:d)RCS/$$(@:f),v : co $@
X.sp
X.RE
XThis rule uses the dynamic macro $@ to specify the prerequisite to try to
Xinfer.  During inference of this rule the macro $@ is set to the value of
Xthe target of the %-meta rule and the appropriate prerequisite is generated by
Xextracting the directory portion of the target name (if any), appending the
Xstring \fIRCS/\fP to it, and appending the target file name with a trailing
X\fI,v\fP attached to the previous result.
X.PP
X.B dmake
Xcan also infer indirect prerequisites.
XAn inferred target can have a list of prerequisites added that will not
Xshow up in the value of $< but will show up in the value of $? and $&.
XIndirect prerequisites are specified in an inference rule by quoting the
Xprerequisite with single quotes.  For example, if you had the explicit
Xdependency:
X.RS
X.sp
X.nf
Xfred.o : fred.c ; rule to make fred.o
Xfred.o : local.h
X.fi
X.sp
X.RE
Xthen this can be inferred for fred.o from the following inference rule:
X.RS
X.sp
X%.o : %.c 'local.h' ; rule to make a .o from a .c
X.sp
X.RE
XYou may infer indirect prerequisites that are a function of the value of '%'
Xin the current rule.  The meta-rule:
X.RS
X.sp
X%.o : %.c '$(INC)/%.h' ; rule to make a .o from a .c
X.sp
X.RE
Xinfers an indirect prerequisite found in the INC directory whose name is the
Xsame as the expansion of $(INC), and the prerequisite name depends on the
Xbase name of the current target.
XThe set of indirect prerequisites is attached to the meta rule in which they
Xare specified and are inferred only if the rule is used to infer a recipe
Xfor a target.  They do not play an active role in driving the inference
Xalgorithm.
XThe construct:
X.RS
X.sp
X%.o : %.c %.f 'local.h'; recipe
X.sp
X.RE
Xis equivalent to:
X.RS
X.sp
X.nf
X%.o : %.c 'local.h' : recipe
X%.o : %.f 'local.h' : recipe
X.fi
X.sp
X.RE
X.PP
XIf any of the attributes .SETDIR, .EPILOG, .PROLOG, .SILENT,
X\&.USESHELL, .SWAP, .PRECIOUS, .LIBRARY, .NOSTATE and .IGNORE
Xare given for a %-rule then when that rule is bound to a target
Xas the result of an inference, the target's set of attributes is augmented by
Xthe attributes from the above set that are specified in the bound %-rule.
XOther attributes specified for %-meta rules are not inherited by the target.
XThe .SETDIR attribute is treated in a special way.
XIf the target already had a .SETDIR attribute set then
X.B dmake
Xchanges to that directory prior to performing the inference.
XDuring inference any .SETDIR attributes for the inferred prerequisite
Xare honored.
XThe directories must exist for a %-meta rule to be selected as a possible
Xinference path.  If the directories do not exist no error message is issued,
Xinstead the corresponding path in the inference graph is rejected.
X.PP
X.B dmake
Xalso supports the old format special target .<suffix>.<suffix>
Xby identifying any rules
Xof this form and mapping them to the appropriate %-rule.  So for example if
Xan old makefile contains the construct:
X.RS
X.sp
X\&.c.o :; cc \-c $< \-o $@
X.sp
X.RE
X.B dmake
Xmaps this into the following %-rule:
X.RS
X.sp
X%.o : %.c; cc \-c $< \-o $@
X.sp
X.RE
XFurthermore,
X.B dmake
Xunderstands several SYSV AUGMAKE special targets and maps them into
Xcorresponding %-meta rules.  These transformation must be enabled by providing
Xthe \-A flag on the command line or by setting the value of AUGMAKE to
Xnon\-NULL.
XThe construct
X.RS
X.sp
X\&.suff :; recipe
X.sp
X.RE
Xgets mapped into:
X.RS
X.sp
X% : %.suff; recipe
X.sp
X.RE
Xand the construct
X.RS
X.sp
X\&.c~.o :; recipe
X.sp
X.RE
Xgets mapped into:
X.RS
X.sp
X%.o : s.%.c ; recipe
X.sp
X.RE
XIn general, a special target of the form .<str>~ is replaced by the %-rule
Xconstruct s.%.<str>, thereby providing support for the syntax used by SYSV
XAUGMAKE for providing SCCS support.
XWhen enabled, these mappings allow processing of existing SYSV
Xmakefiles without modifications.
X.PP
X.B dmake
Xbases all of its inferences on the inference graph constructed from the
X%-rules defined in the makefile.
XIt knows exactly which targets can be made from which prerequisites by
Xmaking queries on the inference graph.  For this reason .SUFFIXES is not
Xneeded and is completely ignored.
X.PP
XFor a %-meta rule to be inferred as the
Xrule whose recipe will be used to make a target, the target's name must match
Xthe %-target pattern, and any inferred %-prerequisite must already exist or
Xhave an explicit recipe so that the prerequisite can be made.
XWithout \fItransitive closure\fP on the inference graph the above rule
Xdescribes precisely when an inference match terminates the search.
XIf transitive closure is enabled (the usual case), and a prerequisite does
Xnot exist or cannot be made, then
X.B dmake
Xinvokes the inference algorithm recursively on the prerequisite to see if
Xthere is some way the prerequisite can be manufactured.  For, if the
Xprerequisite can be made then the current target can also be made using the
Xcurrent %-meta rule.
XThis means that there is no longer a need to give a rule
Xfor making a .o from a .y if you have already given a rule for making a .o
Xfrom a .c and a .c from a .y.  In such cases
X.B dmake
Xcan infer how to make the
X\&.o from the .y via the intermediary .c and will remove the .c when the .o is
Xmade.  Transitive closure can be disabled by giving the \-T switch on the
Xcommand line.
X.PP
XA word of caution.
X.B dmake
Xbases its transitive closure on the %-meta rule targets.
XWhen it performs transitive closure it infers how to make a target from a
Xprerequisite by performing a pattern match as if the potential prerequisite
Xwere a new target.
XThe set of rules:
X.RS
X.nf
X.sp
X%.o : %.c :; rule for making .o from .c
X%.c : %.y :; rule for making .c from .y
X% : RCS/%,v :; check out of RCS file
X.fi
X.sp
X.RE
Xwill, by performing transitive closure, allow \fBdmake\fP to infer how to make
Xa .o from a .y using a .c as an intermediate temporary file.  Additionally
Xit will be able to infer how to make a .y from an RCS file, as long as that
XRCS file is in the RCS directory and has a name which ends in .y,v.
XThe transitivity computation is performed dynamically for each target that
Xdoes not have a recipe.  This has potential to be costly if the %-meta
Xrules are not carefully specified.  The .NOINFER attribute is used to mark
Xa %-meta node as being a final target during inference.  Any node with this
Xattribute set will not be used for subsequent inferences.  As an example
Xthe node RCS/%,v is marked as a final node since we know that if the RCS file
Xdoes not exist there likely is no other way to make it.  Thus the standard
Xstartup makefile contains an entry similar to:
X.RS
X.nf
X\&.NOINFER : RCS/%,v
X.fi
X.RE
XThereby indicating that the RCS file is the end of the inference chain.
XX
XWhenever the inference algorithm determines that a target can be made from
Xmore than one prerequisite and the inference chains for the two methods
Xare the same length the algorithm reports an ambiguity and prints the
Xambiguous inference chains.
X.PP
X.B dmake
Xtries to
Xremove intermediate files resulting from transitive closure if the file
Xis not marked as being PRECIOUS, or the \fB\-u\fP flag was not given on the
Xcommand line, and if the inferred intermediate did not previously exist.
XIntermediate targets that existed prior to being made are never removed.
XThis is in keeping with the philosophy that
X.B dmake
Xshould never remove things from the file system that it did not add.
XIf the special target .REMOVE is defined and has a recipe then
X.B dmake
Xconstructs a list of the intermediate files to be removed and makes them
Xprerequisites of .REMOVE.  It then makes .REMOVE thereby removing the
Xprerequisites if the recipe of .REMOVE says to.  Typically .REMOVE is defined
Xin the startup file as:
X.sp
X\t.REMOVE :; $(RM) $<
X.SH "MAKING TARGETS"
XIn order to update a target \fBdmake\fP must execute a recipe.
XWhen a recipe needs to be executed it is first expanded so that any macros
Xin the recipe text are expanded, and it is then either executed directly or
Xpassed to a shell.
X.B dmake
Xsupports two types of recipes.  The regular recipes and group recipes.
X.PP
XWhen a regular recipe is invoked \fBdmake\fP executes each line of the recipe
Xseparately using a new copy of a shell if a shell is required.
XThus effects of commands do not generally persist across recipe lines.
X(e.g. cd requests in a recipe line do not carry over to the next recipe line)
XThe decision on whether a shell is required to execute a command is based on
Xthe value of the macro SHELLMETAS or on the specification of '+' or .USESHELL
Xfor the current recipe or target respectively.
XIf any character in the value of
XSHELLMETAS is found in the expanded recipe text-line or the use of a shell
Xis requested explicitly via '+' or .USESHELL then the command is
Xexecuted using a shell, otherwise the command is executed directly.
XThe shell that is used for execution is given by the value of the macro SHELL.
XThe flags that are passed to the shell are given by the value of SHELLFLAGS.
XThus \fBdmake\fP constructs the command line:
X.sp
X\t$(SHELL) $(SHELLFLAGS) $(expanded_recipe_command)
X.sp
XNormally
X.B dmake
Xwrites the command line that it is about to invoke to standard output.
XIf the .SILENT attribute is set for the target or for
Xthe recipe line (via @), then the recipe line is not echoed.
X.PP
XGroup recipe processing is similar to that of regular recipes, except that
Xa shell is always invoked.  The shell that is invoked is given by the value of
Xthe macro GROUPSHELL, and its flags are taken from the value of the macro
XGROUPFLAGS.  If a target has the .PROLOG attribute set then
X.B dmake
Xprepends to the shell script the recipe associated with the special target
X\&.GROUPPROLOG, and if the attribute .EPILOG is set as well, then the recipe
Xassociated with the special target .GROUPEPILOG is appended to the script
Xfile.
XThis facility can be used to always prepend a common header and common trailer
Xto group recipes.
XGroup recipes are echoed to standard output just like standard recipes, but
Xare enclosed by lines beginning with [ and ].
X.PP
XThe recipe flags [+,\-,%,@] are recognized at the start of a recipe line
Xeven if they appear in a macro.  For example:
X.RS
X.sp
X.nf
XSH = +
Xall:
X\t$(SH)echo hi
X.fi
X.sp
X.RE
Xis completely equivalent to writing
X.RS
X.sp
X.nf
XSH = +
Xall:
X\t+echo hi
X.fi
X.sp
X.RE
X.PP
XThe last step performed by
X.B dmake
Xprior to running a recipe is to set the macro CMNDNAME to the name of the
Xcommand to execute (determined by finding the first white\-space ending token
SHAR_EOF
true || echo 'restore of dm37p2 failed'
fi
echo 'End of  part 6'
echo 'File dm37p2 is continued in part 7'
echo 7 > _shar_seq_.tmp
exit 0

exit 0 # Just in case...
-- 
Kent Landfield                   INTERNET: kent at sparky.IMD.Sterling.COM
Sterling Software, IMD           UUCP:     uunet!sparky!kent
Phone:    (402) 291-8300         FAX:      (402) 291-4362
Please send comp.sources.misc-related mail to kent at uunet.uu.net.