Was: "Dart (Swift) like multi line strings indentation"
This discussion petered-out but I liked the idea, as it alleviates something
occasionally annoying.
Am supportive of the d'' prefix, perhaps the capital prefixes can be deprecated
to avoid issues? If not, a sometimes-optimized (or C-accelerated) str.dedent()
is acceptable too.
Anyone still interested in this?
-Mike
On 3/31/18 5:43 PM, Steven D'Aprano wrote:
The ideal solution would:
- require only a single pair of starting/ending string delimiters;
- allow string literals to be indented to the current block, for
the visual look and to make it more convenient with editors
which automatically indent;
- evaluate without the indents;
- with no runtime cost.
One solution is to add yet another string prefix, let's say d for
dedent, but as Terry and others point out, that leads to a combinational
explosion with f-strings and r-strings already existing.
Another possibility is to make dedent a string method:
def spam():
text = """\
some text
another line
and a third
""".dedent()
print(text)
and avoid the import of textwrap. However, that also imposes a runtime
cost, which could be expensive if you are careless:
for x in seq:
for y in another_seq:
process("""/
some large indented string
""".dedent()
)
(Note: the same applies to using textwrap.dedent.)
But we could avoid that runtime cost if the keyhole optimizer performed
the dedent at compile time:
triple-quoted string literal
.dedent()
could be optimized at compile-time, like other constant-folding.
Out of all the options, including the status quo, the one I dislike the
least is the last one:
- make dedent a string method;
- recommend (but don't require) that implementations perform the
dedent of string literals at compile time;
(failure to do so is a quality of implementation issue, not a bug)
- textwrap.dedent then becomes a thin wrapper around the string method.
On 4/1/18 4:41 AM, Michel Desmoulin wrote:>
> A "d" prefix to do textwrap.dedent is something I wished for a long time.
>
> It's like the "f" one: we already can do it, be hell is it convenient to
> have a shortcut.
>
> This is especially if, like me, you take a lot of care in the error
> messages you give to the user. I write a LOT of them, very long, very
> descriptive, and I have to either import textwrap or play the
> concatenation game.
>
> Having a str.dedent() method would be nice, but the d prefix has the
> huge advantage to be able to dedent on parsing, and hence be more
> performant.
>
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