[CMake] How to not evaluate variable names ?

[David Cole]

so if you have this:  macro(blah arg1)
    message("==${arg1}==")
  endmacro(blah)

  blah("${do_not_evaluate}")
  blah("\${do_not_evaluate}")
  blah("\\\${do_not_evaluate}")

you should see:
====
====
==${do_not_evaluate}==

I'm using CMake 2.6.4 to get these results. I think 2.4.8 should give you
the same...

Because you are calling through a macro and there are multiple (in this case
2) levels of de-referencing happening, you need extra escaping to get the
desired effect.

I think you should be ok "as-is" with your code if you have the right number
of escapes in there. Stuff like this is sensitive, though, and there might
be a better way to approach it rather than adding escape characters till it
works... (Re-design with the intent of passing ${xyz} string literals
through the system without multiple levels of escaping...)

If you could post some code (or simplify it) others may be able to offer
some more helpful suggestions.


HTH,
David


On Wed, Sep 30, 2009 at 8:09 AM, <fred.antares at free.fr> wrote:

> The problem is I'm working on quite a big project, and it was not written
> initially by me. I don't know about the "FILE(WRITE", but here's what I'm
> doing:
> - In the CMakelists, I'm calling a macro with one of the parameters being
> what I
> want in my attribute (in that case "${do_not_evaluate}").
> - This macro adds the attribute to a specific source group
> - The source group is parsed and interpreted by custom code that was added
> to
> CMake for our own generation needs
> - The arg ends up being added to a Tiny XML element
> - The XML file write is done from the custom code, by calling Write on the
> Tiny
> XML hierarchy
>
> The CMake version is 2.4.8, but customized with our own generators.
>
> Maybe the simpler thing, given the case and the lack of a direct solution,
> would
> be to add a specific string to the attribute, signaling to the code that it
> should be replaced ?
>
> Fred
>
> Quoting David Cole <david.cole at kitware.com>:
>
> > Are you using "FILE(WRITE"...?
> > What version of CMake?
> >
> > This should work. Send the CMake code snippet you are using to try to do
> > this so that we can see what might be wrong.
> >
> > If using older CMake (2.4.something) then you may have to do:
> >   set(DOLLAR "$")
> >   file(WRITE blah "${DOLLAR}{varNameHere}")
> >
> > ...but escaping the "$" inside a string literal has worked for quite some
> > time now... I'd like to know if you have a different use case or are just
> > seeing older-versioned CMake behavior.
> >
> >
> >
> > On Wed, Sep 30, 2009 at 3:54 AM, <fred.antares at free.fr> wrote:
> >
> > > Quoting Marcel Loose <loose at astron.nl>:
> > >
> > > > On Wed, 2009-09-30 at 09:28 +0200, fred.antares at free.fr wrote:
> > > > > Quoting Jeroen Dierckx <jeroen.dierckx at gmail.com>:
> > > > >
> > > > > > On Wed, Sep 30, 2009 at 8:32 AM, <fred.antares at free.fr> wrote:
> > > > > >
> > > > > > > Hi,
> > > > > > >
> > > > > > > I've seen a previous discussion on this subject, but
> unfortunately,
> > > > none of
> > > > > > > the
> > > > > > > given solutions (as described on
> > > > > > > http://www.cmake.org/Wiki/CMake:VariablesListsStrings) seem to
> > > work in
> > > > my
> > > > > > > case.
> > > > > > >
> > > > > > > I'm using CMake to generate an XML config file, and one of the
> tags
> > > > must
> > > > > > > have an
> > > > > > > argument as follows: args="${serverConfigChanged}". The XML is
> used
> > > by
> > > > > > > CruiseControl, and unfortunately, it uses the same variable
> syntax
> > > as
> > > > > > > CMake. I
> > > > > > > tried almost every combination of escaping, double dollars, but
> > > > couldn't
> > > > > > > get the
> > > > > > > correct output.
> > > > > > >
> > > > > > > Is there some way to achieve that directly from the
> CMakeList.txt,
> > > or
> > > > > > > should I
> > > > > > > do that in the generator code ?
> > > > > > >
> > > >
> > > > Hi Jeroen,
> > > >
> > > > What about:
> > > >
> > > > file(WRITE /tmp/dummy.xml "args=\"\${serverConfigChanged}\"\n")
> > > >
> > > > That works for me. You must escape the double quotes (") and the
> dollar
> > > > sign ($).
> > > >
> > > > Best regards,
> > > > Marcel Loose.
> > > >
> > > >
> > >
> > > Unfortunately, it doesn't work. I already tried escaping the dollar
> sign
> > > and the
> > > result in that case is args="".
> > >
> > > Fred
> > >
> > >
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>
>
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