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Clarify what the underscores actually mean.

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Georg Brandl 2016-02-11 17:58:09 +01:00
parent eb4e4467a9
commit 2c56f53fcb
1 changed files with 8 additions and 6 deletions
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14
pep-0515.txt
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@ -13,8 +13,9 @@ Post-History: 10-Feb-2016, 11-Feb-2016
Abstract and Rationale
======================
This PEP proposes to extend Python's syntax so that underscores can be used in
integral, floating-point and complex number literals.
This PEP proposes to extend Python's syntax so that underscores can be used as
visual separators for digit grouping purposes in integral, floating-point and
complex number literals.
This is a common feature of other modern languages, and can aid readability of
long literals, or literals whose value should clearly separate into parts, such
@ -39,7 +40,8 @@ Specification
=============
The current proposal is to allow one or more consecutive underscores following
digits and base specifiers in numeric literals.
digits and base specifiers in numeric literals. The underscores have no
semantic meaning, and literals are parsed as if the underscores were absent.
The production list for integer literals would therefore look like this::
@ -47,9 +49,9 @@ The production list for integer literals would therefore look like this::
decimalinteger: nonzerodigit (digit | "_")* | "0" ("0" | "_")*
nonzerodigit: "1"..."9"
digit: "0"..."9"
octinteger: "0" ("o" | "O") (octdigit | "_")*
hexinteger: "0" ("x" | "X") (hexdigit | "_")*
bininteger: "0" ("b" | "B") (bindigit | "_")*
octinteger: "0" ("o" | "O") "_"* octdigit (octdigit | "_")*
hexinteger: "0" ("x" | "X") "_"* hexdigit (hexdigit | "_")*
bininteger: "0" ("b" | "B") "_"* bindigit (bindigit | "_")*
octdigit: "0"..."7"
hexdigit: digit | "a"..."f" | "A"..."F"
bindigit: "0" | "1"