[PATCH] templater: add 'env()' to fetch environment variables

[Matt Harbison]

On Tue, 17 Jan 2017 07:51:26 -0500, Yuya Nishihara <yuya at tcha.org> wrote:

> On Mon, 16 Jan 2017 22:28:17 -0500, Matt Harbison wrote:
>> On Mon, 16 Jan 2017 07:25:24 -0500, Yuya Nishihara <yuya at tcha.org>  
>> wrote:
>> > This can be a simple {env} (or {environ}) keyword and you can use  
>> get()
>> > function, e.g. {get(env, 'pattern')}. showextras() is a good example  
>> of
>> > building template dict.
>>
>> I've got to be missing something simple.  I added this code:
>>
>> @templatekeyword('environ')
>> def showenviron(**args):
>>      """A dictionary of environment variables."""
>>
>>      env = encoding.environ
>>      env = util.sortdict((k, env[k]) for k in sorted(env))
>>      makemap = lambda k: {'key': k, 'value': env[k]}
>>      c = [makemap(k) for k in env]
>>      f = _showlist('environ', c, **args)
>>      return _hybrid(f, env, makemap,
>>                     lambda x: '%s=%s' % (x['key'], x['value']))
>>
>> And these forms work:
>>
>> $ pattern=foo ../hg log -r . -T "{get(environ, 'PATTERN')}"
>> foo
>> $ pattern=foo ../hg log -r . -T "{environ % '{key} -> {value}\n'}"
>> !:: -> ::\
>> ALLUSERSPROFILE -> C:\ProgramData
>> ...
>>
>> But this doesn't.  It spews a wall of text that looks like templater
>> internals:
>>
>> $ pattern=foo ../hg log -r . -T "{environ}"
>> filestermwidthnamespacesrevcachetroublesobsoleteactivebookmarkdatep1nodebookmarks...
>>
>> The {extras} template that I copy/pasted from lists key=value lines.  I
>> also looked at 'namespaces', but couldn't figure out what triggered  
>> this.
>
> The bare {extras} is rendered by _showlist() as an old-style template,  
> and
> it appears _showlist() can't process dict values if no template provided.
> (It somehow yields a dict of full args.)
>
> https://www.mercurial-scm.org/repo/hg/file/4.0.2/mercurial/templatekw.py#l89
>
> One way to avoid spilling out the internal variables is to set the  
> default
> 'environ' template.

Thanks! I never would have noticed that.

I see that the default template for 'extras' filters through  
'stringescape', which isn't documented, so it isn't in the help.  Any  
reason it shouldn't be documented?

> https://www.mercurial-scm.org/repo/hg/file/4.0.2/mercurial/cmdutil.py#l1507
>
> Another problem is the 'environ' keyword conflict with the 'environ'  
> template.
> We'll have to pick a plural name (e.g. 'envs', 'environs', 'envvars'.)