On 27/03/2015 20:48, Ian Kelly wrote:
On Fri, Mar 27, 2015 at 2:24 PM, Jamie Willis
<jw14896.2...@my.bristol.ac.uk> wrote:
I would like to propose a new piece of syntax for the python language; .=
In short, the operator is form of syntactic sugar, for instance consider the
following code:
hello = "hello world "
hello = hello.strip()
This could be written as:
hello = "hello world "
hello .= strip()
In this slightly contrived example, the programmer saved (a small amount of)
time when writing the code. With code with longer variable names, or lots of
similar statements all in a row, this helps to keep code more concise.
The operator would be constricted to one method or field on the right-hand
side, which must belong to the object on the left hand side.
Another example could be when using Linked Lists, instead of writing
something like:
loop_node = loop_node.next
you could write:
loop_node .= next
An alternate syntax might be:
hello = .string()
loop_node =. next
With flexible white space either side of "." unless it is important that
".=" or "=." is a single token.
I'm assuming that an isolated "." is not a valid starter symbol for
anything else, other than a floating point constant such as hello =.3
On the minus side it seems marginal in utility to me, as all it does
is save a bit of typing. The +=, etc. operators are backed by special
methods named __iadd__ etc. which allows the class author to provide
for the operation to be performed in-place, or to change the meaning
entirely use the operator as part of a DSL. This proposal doesn't have
any room that I can see for that sort of benefit.
It needn't require that sort of support. It does just save typing in the
same way that A += B does, and makes it a little clearer what is being
expressed. Except that with A = .B, A will be evaluated twice.
--
Bartc
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