diff options
| -rw-r--r-- | make.texinfo | 23 |
1 files changed, 14 insertions, 9 deletions
diff --git a/make.texinfo b/make.texinfo index 85375bb..0a70f20 100644 --- a/make.texinfo +++ b/make.texinfo @@ -4174,16 +4174,20 @@ it is this unexpanded text to which @code{make} appends the new text you specify. @example +@group variable = value variable += more +@end group @end example @noindent is roughly equivalent to: @example +@group temp = value variable = $(temp) more +@end group @end example @noindent @@ -4213,15 +4217,16 @@ CFLAGS := $(CFLAGS) -pg # enable profiling @end example @noindent -This is close, but not quite what we want. Using @samp{:=} redefines -@code{CFLAGS} as a simply-expanded variable; this means @code{make} expands -the text @w{@samp{$(CFLAGS) -pg}} before setting the variable. If -@code{includes} is not yet defined, we get @w{@samp{ -O -pg}}, and a later -definition of @code{includes} will have no effect. Conversely, by using -@samp{+=} we set @code{CFLAGS} to the @emph{unexpanded} value -@w{@samp{$(includes) -O -pg}}. Thus we preserve the reference to -@code{includes}, so if that variable gets defined at any later point, a -reference like @samp{$(CFLAGS)} still uses its value. +This is pretty close, but not quite what we want. Using @samp{:=} +redefines @code{CFLAGS} as a simply-expanded variable; this means +@code{make} expands the text @w{@samp{$(CFLAGS) -pg}} before setting the +variable. If @code{includes} is not yet defined, we get @w{@samp{ -O +-pg}}, and a later definition of @code{includes} will have no effect. +Conversely, by using @samp{+=} we set @code{CFLAGS} to the +@emph{unexpanded} value @w{@samp{$(includes) -O -pg}}. Thus we preserve +the reference to @code{includes}, so if that variable gets defined at +any later point, a reference like @samp{$(CFLAGS)} still uses its +value. @node Override Directive, Defining, Appending, Using Variables @section The @code{override} Directive |