Python Feature Request: Add the "using" keyword which works like "with" in Visual Basic

samjnaa at gmail.com samjnaa at gmail.com
Sat Apr 14 12:42:52 CEST 2007


Please check for sanity and approve for posting at python-dev.

In Visual Basic there is the keyword "with" which allows an object-
name to be declared as governing the following statements. For
example:

with quitCommandButton
 .enabled = true
 .default = true
end with

This is syntactic sugar for:

quitCommandButton.enabled=true
quitCommandButton.default=true

This can be very useful especially in GUI programming when we have to
type the same object name in line-after-line. I personally found
having to type the word "self" umpteen times inside classes very
irritating. Such a beautiful language is Python, she should have this
good feature from VB too.

Now I hear that the word "with" is being discussed for a different
purpose in Py 3 as a result of a PEP and I don't want to conflict with
that. So I propose the word "using" as a replacement. This also is
similar to the C++ "using" keyword which exposes the members of a
namespace to access without specifying the namespace scope for each
reference. For example after giving "using namespace std;" I can
change all references to "std::cout" to "cout", which is similar to
what I am proposing for Python now.

Some thoughts about how this "using" statement should behave. The word
using should be followed by an object name and a colon indicating the
start of a block. The object named after "using" must determine the
context (or whatever the technical word is) of the of the statements
in that block.

self.setFixedSize(200, 120)
self.quit = QtGui.QPushButton("Quit", self)
self.quit.setGeometry(62, 40, 75, 30)
self.quit.setFont(QtGui.QFont("Times", 18, QtGui.QFont.Bold))
self.connect(self.quit, QtCore.SIGNAL("clicked()"), QtGui.qApp,
QtCore.SLOT("quit()"))

to be rewritten as:

using self:
__setFixedSize(200,120)
__quit = QtGui.QPushButton("Quit", self)
__using quit:
____setGeometry(62, 40, 75, 30)
____setFont(QtGui.QFont("Times", 18, QtGui.QFont.Bold))
__connect(self.quit, QtCore.SIGNAL("clicked()"), QtGui.qApp,
QtCore.SLOT("quit()"))

[I don't know whether usenet will retain my indenting, so I changed
the tabs to underscores.]

This context governing may need to be limited to the first applicable
member - so that in the above example "self" governs setFixedSize,
quit, quit and connect only in each sentence and quit (self.quit)
governs setGeometry and setFont only. (Point is that the parser should
not search for self.QtGui, self.self or self.QtCore in sentences 3 and
7, and self.quit.QtGui in sentence 6.)

Due to my absence of professional experience, my request may be
somewhat unpolished technical-wise, but I believe that this is a very
useful feature for Python and hence request the technically-
knowledgeable to reformat it as necessary. Thank you.




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