Re: [RFC PATCH 1/2] Add $_env convenience function

[Keith Seitz <keiths@redhat.com>]

On 2/3/23 09:18, Andrew Burgess wrote:

>> diff --git a/gdb/python/lib/gdb/function/env.py b/gdb/python/lib/gdb/function/env.py
>> new file mode 100644
>> index 00000000000..54a441cea54
>> --- /dev/null
>> +++ b/gdb/python/lib/gdb/function/env.py
>> @@ -0,0 +1,21 @@
> 
> Missing copyright header here.

It *was* just an RFC. :-P

I will, of course, add appropriate header, copyright, etc
when I submit for final approval (after I write a few tests
and docs).

I will submit independently of the expression-evaluation
substitution patch (#2 in this series).

> 
>> +"""$_env"""
>> +
>> +import gdb
>> +import os
>> +
>> +class _Env(gdb.Function):
>> +    """$_env - return the value of an environment variable.
>> +
>> +    Usage: $_env("NAME")
>> +
>> +    Returns:
>> +      Value of the environment variable named NAME or throws KeyError if NAME is
>> +      undefined in the environment."""
>> +
>> +    def __init__(self):
>> +        super(_Env, self).__init__("_env")
>> +
>> +    def invoke(self, name):
>> +        return os.environ[name.string()]
> 
> Something like this:
> 
>      def invoke(self, name, default=None):
>          if default is not None and not name.string() in os.environ:
>            return default
>          return os.environ[name.string()]
> 
> would allow users to supply a default:
> 
>    p $_env("UNKNOWN", "default_value")
> 
> But retains:
> 
>    p $_env("HOME")
> 
> Might be useful?

That's a very good idea. I'll steal that. :-)

Keith