[Scons-users] [Scons-dev] env.subst and variable substitution including whitespace in parameters

[Bill Deegan]

Really shouldn't need to run paths through subst to get the strings
properly escaped (or quoted depending on the platform)..

Can you create a small testcase demonstrating the problem, and I'll take a
look at it in a few days when I'm back from vacation..

On Mon, Sep 17, 2018 at 8:03 PM RW via Scons-users <scons-users at scons.org>
wrote:

> Sorry I'll keep any replies to the user list,
> I'm basically piping in a string from python then capturing the output and
> using the results in python
> so I'm capturing stdin and stdout. PSPAWN might work thanks for the info
>
> I did also find another example where env.subst_list is useful
> if you have a list of paths stored in an env variable, and those paths
> contain spaces
>
> ```
> env.Replace(Example1=['D:\\Temp\Test Folder 1\\src1.c'])
> env.Append(Example1=['D:\\Temp\Test Folder 1\\src2.c'])
> env.Append(Example1=['D:\\Temp\Test Folder 1\\src3.c'])
>
> env.Replace(Example2=['D:\\Temp\Test Folder 1\\src4.c'])
> env.Append(Example2=['D:\\Temp\Test Folder 1\\src5.c'])
> env.Append(Example2=['D:\\Temp\Test Folder 1\\src6.c'])
>
> env.Replace(SRCS='$Example1 $Example2')
>
> # This doesn't work due to spaces in path
> #items = env.Split('$SRCS')
>
> # This results in a single string with unescaped paths
> # making it difficult to split them apart or escape them
> #items = env.subst('$SRCS')
>
> items = env.subst_list('$SRCS')[0]
> for item in items:
>     print(item)
> ```
>
> this is why I was wondering if having env.subst_list as some form of
> public api should be on the github issues / todo list
> to give some context, this is what the Preprocess tool I've written looks
> like so far
>
> ```
> def generate(env):
>     env.AddMethod(PreProcessStream, 'PreProcessStream')
>
>
> def PreProcessStream(env, stdin_str):
>     # Handle escaping / quoting variable expansion
>     escape = env.get('ESCAPE', lambda x: x)
>     escape_list = SCons.Subst.escape_list
>
>     cmdstr = '${CPP} -E ${CFLAGS} ${CCFLAGS} ${_CCCOMCOM} -'
>     cmd_list = env.subst_list(cmdstr, SCons.Subst.SUBST_CMD)
>
>     cmd_list = escape_list(cmd_list[0], escape)
>     cmd = ' '.join(cmd_list)
>
>     p = subprocess.Popen(cmd, stdout=subprocess.PIPE,
> stdin=subprocess.PIPE, stderr=subprocess.PIPE)
>     out, err = p.communicate(input=stdin_str.encode())
>     return out, err
> ```
>
> Many Thanks
> Richard
>
>
> On Mon, 17 Sep 2018 at 19:47, Mats Wichmann <mats at wichmann.us> wrote:
>
>> On 09/17/2018 12:07 PM, Bill Deegan wrote:
>> > Did you try having pipes in your action command string?
>> > I'm thinking it should work..
>> >
>> > I wrote the wiki page you mentioned and it's a WIP.
>>
>> >> I'm wondering if this should be filed as a github issue
>> >>
>> >> Recently I ran into a problem, I needed to write a method to pipe some
>> >> input into and out of gcc via the preprocessor
>> >> this meant using subprocess instead of calling an scons Action since I
>> >> wanted to do piping, but to do that I needed to expand outwards the
>> gcc /
>> >> cpppath etc into a string.
>>
>> there is some mechanism for piping in a command, see the PSPAWN
>> construction environment variable.
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