06-23-2010
Quote:
Originally Posted by
Narnie
Why doesn't the value of x change to 6 in the above example? I'm I "redefining" self in the value() method to no longer reflect what is self in the instance?
If you read up on the
Python Data Model, you will see that numbers (actually all numerics) are implemented as an immutable (aka. not-changeable) type. This would mean that you could never (using Python numerics) implement something such that 2+2=5 (for all extremely large values of 2
)
Quote:
Originally Posted by
Narnie
How does the value of x become incremented internally? What magic is happening behind the scenes?
No magic really. What is happening (even with your shorthand) is a replacement operator. The right side is evaluated, and then the left side is re-pointed to the new value (so the old value is essentially lost). You have to watch out when you use this though, because the immutable/mutable types each act differently...
Read this for more info...
Quote:
Originally Posted by
Narnie
Say I want to do what is verboten in Python. Make in C-like incrementor like this.
It depends on how far you are willing to go to get a "proper solution". If you want to use the "++" or "--" in-line in Python, be prepared to write the extension in C/C++ and to recompile Python just for you. You would basically be writing "object.__iplusplus__" (or something pretty close) - Again reference the Data Model to give you an idea where to look in the
Python Source.
Either way you head, I applaud you for not jumping ship at the whitespace-strictness.
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LEARN ABOUT DEBIAN
dh_python
DH_PYTHON(1) Debhelper DH_PYTHON(1)
NAME
dh_python - calculates Python dependencies and adds postinst and prerm Python scripts (deprecated)
SYNOPSIS
dh_python [debhelperoptions] [-n] [-V version] [moduledirs...]
DESCRIPTION
Note: This program is deprecated. You should use dh_python2 instead. This program will do nothing if debian/pycompat or a Python-Version
control file field exists.
dh_python is a debhelper program that is responsible for generating the ${python:Depends} substitutions and adding them to substvars files.
It will also add a postinst and a prerm script if required.
The program will look at Python scripts and modules in your package, and will use this information to generate a dependency on python, with
the current major version, or on pythonX.Y if your scripts or modules need a specific python version. The dependency will be substituted
into your package's control file wherever you place the token ${python:Depends}.
If some modules need to be byte-compiled at install time, appropriate postinst and prerm scripts will be generated. If already byte-
compiled modules are found, they are removed.
If you use this program, your package should build-depend on python.
OPTIONS
module dirs
If your package installs Python modules in non-standard directories, you can make dh_python check those directories by passing their
names on the command line. By default, it will check /usr/lib/site-python, /usr/lib/$PACKAGE, /usr/share/$PACKAGE,
/usr/lib/games/$PACKAGE, /usr/share/games/$PACKAGE and /usr/lib/python?.?/site-packages.
Note: only /usr/lib/site-python, /usr/lib/python?.?/site-packages and the extra names on the command line are searched for binary (.so)
modules.
-V version
If the .py files your package ships are meant to be used by a specific pythonX.Y version, you can use this option to specify the
desired version, such as 2.3. Do not use if you ship modules in /usr/lib/site-python.
-n, --noscripts
Do not modify postinst/prerm scripts.
CONFORMS TO
Debian policy, version 3.5.7
Python policy, version 0.3.7
SEE ALSO
debhelper(7)
This program is a part of debhelper.
AUTHOR
Josselin Mouette <joss@debian.org>
most ideas stolen from Brendan O'Dea <bod@debian.org>
9.20120909 2011-12-06 DH_PYTHON(1)