In Python 2 the syntax to catch exceptions was:
except (Exception1, Exception2), target:
In Python 3 the syntax to catch exceptions is:
except (Exception1, Exception2) as target:
This newer Python 3 syntax is also available in 2.6 and 2.7. Therefore,
it is preferred for compatibility reasons. Additionally, the target no
longer can be a tuple. This patch refactors the exception handeling code
to be the newer Python 3 exception catch syntax.
The `StringIO` and `cStringIO` modules are gone in Python 3. The
recommendation is to import the `io` module on Python 3. Therefore, this
patch first attempts to import the Python 2 module, `cStringIO`, and if
that fails then attempts to import the Python 3 module, `io`.
**NOTE**: There are still other Python 3.x fixes necessary to make `gyb`
run on a Python 3.x interpreter. This is just one small incremental
patch on the way there.
[PEP 3114](https://www.python.org/dev/peps/pep-3114/) renamed
`iterator.next()` (Python 2) to `iterator.__next__()` (Python 3). The
recommended solution to make the code work in both Python 2 and 3 is to
call the global `next` function.
To use this recommended global `next` function this patch uses a lambda
function to supply `tokenize.generate_tokens` a callable function as it was previously.
This should be functionally equivalent to the old code with the added
benefit of working on both Python 2 and 3.
Rather than using `f = open(path).read()`, which leaves the file open
for an indeterminate period of time, switch to the `with open(path) as f`
idiom, which ensures the file is always closed correctly.
In Python 3, 'print' was changed from a statement to a function. Using
the __future__ module allows scripts to use print function whether
running with Python 2.6+ or Python 3.x. This commit changes as many
instances of print as I could find to use the print function and the
__future__ module.
This allows Python or .gyb files to do "import gyb" and use the basic
components of the system. For example, we could create a Python
function to generate the boilerplate for a Mirror. That function could
use gyb.parseTemplate() to load an inline template and
gyb.executeTemplate() to generate the code. Then calls to that function
can be embedded in ${...} in a .gyb file.
Swift SVN r19490
