simplify python function definitions

[jimexist]

Which issue does this PR close?

Closes #479
Depends on #483

Rationale for this change

What changes are included in this PR?

Are there any user-facing changes?

[jorgecarleitao]

Thanks a lot, @jimexist . This makes sense, however, I have a question, though:

pyo3 uses rusts' docs (///) to populate Python's documentation. Maybe there is a way to do it via a macro, but atm this increases the barrier to add doc strings to the functions, no? I.e. how do we add a docstring to say ascii in this new code base?

[codecov-commenter]

Codecov Report

Merging #477 (03432e5) into master (e713bc3) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #477   +/-   ##
=======================================
  Coverage   75.95%   75.95%           
=======================================
  Files         154      154           
  Lines       26349    26349           
=======================================
  Hits        20014    20014           
  Misses       6335     6335           

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[jimexist]

Thanks a lot, @jimexist . This makes sense, however, I have a question, though:

pyo3 uses rusts' docs (///) to populate Python's documentation. Maybe there is a way to do it via a macro, but atm this increases the barrier to add doc strings to the functions, no? I.e. how do we add a docstring to say ascii in this new code base?

maybe this will work?

[jimexist]

In [3]: from datafusion import functions as f

In [4]: dir(f)
Out[4]:
['__all__',
 '__doc__',
 '__loader__',
 '__name__',
 '__package__',
 '__spec__',
 'array',
 'ascii',
 'avg',
 'bit_length',
 'btrim',
 'character_length',
 'chr',
 'col',
 'concat_ws',
 'count',
 'in_list',
 'initcap',
 'left',
 'lit',
 'lower',
 'lpad',
 'ltrim',
 'max',
 'md5',
 'min',
 'now',
 'octet_length',
 'random',
 'regexp_replace',
 'repeat',
 'replace',
 'reverse',
 'right',
 'rpad',
 'rtrim',
 'sha224',
 'sha256',
 'sha384',
 'sha512',
 'split_part',
 'starts_with',
 'strpos',
 'substr',
 'sum',
 'to_hex',
 'translate',
 'trim',
 'udaf',
 'udf',
 'upper']

In [5]: f.ascii??
Docstring: Returns the numeric code of the first character of the argument. In UTF8 encoding, returns the Unicode code point of the character. In other multibyte encodings, the argument must be an ASCII character.
Type:      builtin_function_or_method

[jimexist]

error is likely not relevant, merge after fix in #468