Re: target variable ($@) as prerequisite

[Oleksandr Gavenko]

On 26.01.2011 11:46, ulugutz wrote:
> Oleksandr Gavenko-2 wrote:
> > On 26.01.2011 9:20, ulugutz wrote:
> > > Hi,
> > >
> > > how can you for example do this
> > > ------------------------------------
> > > PICS=%.pdf
> > >
> > > all: PICS
> > > PICS: $(@:pdf=.png)
> > >           do something
> > > ------------------------------------
> > > i would really appreciate your help and sorry if it has been posted
> > > already
> > > but I only checked the newest pages of the forum
> > Why not use:
> >
> > PNG_FILES := $(wildcard *.png)
> > PDF_FILES := $(PNG_FILES:.png=.pdf)
> >
> > all: $(PDF_FILES)
> >
> > %.pdf: %.png
> >         png2pdf -o $@ $*.png
> >
> > or last rule can be rewritten as:
> >
> > $(PDF_FILES): %.pdf: %.png
> >         png2pdf -o $@ $*.png
>
> that's more or less what I am currently using. but in this case he 
rebuilds
> ALL pdf files if only one png changes
>
No. You wrong. Only that .pdf for which .png was changed.

Usually this happen then you place in dependency to pattern target
'.PHONY' target:

.PHONY: BADTARGET
BADTARGET:
        command-for-BADTARGET

$(PDF_FILES): %.pdf: %.png BADTARGET
        png2pdf -o $@ $*.png

In this case .pdf file was rebuilt as  BADTARGET always was rebuilt.

Or may be 'png2pdf' command incorrect set last-modification time for .pdf
You can manually fix it by:

touch $@

Please check you Makefile.

--
С уважением, Александр Гавенко.