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Diffstat (limited to 'site/docs/skylark/concepts.md')
| -rw-r--r-- | site/docs/skylark/concepts.md | 35 |
1 files changed, 32 insertions, 3 deletions
diff --git a/site/docs/skylark/concepts.md b/site/docs/skylark/concepts.md index 040654fe64..f2f80437f7 100644 --- a/site/docs/skylark/concepts.md +++ b/site/docs/skylark/concepts.md @@ -238,9 +238,9 @@ comprehension. When the flag is set to true, `depset` objects are not treated as iterable. If you need an iterable, call the `.to_list()` method. This affects `for` loops and -many functions, e.g. `list`, `tuple`, `min`, `max`, `sorted`, `all`, `any`. The -goal of this change is to avoid accidental iteration on `depset`, which can be -expensive. +many functions, e.g. `list`, `tuple`, `min`, `max`, `sorted`, `all`, and `any`. +The goal of this change is to avoid accidental iteration on `depset`, which can +be expensive. ``` python deps = depset() @@ -255,6 +255,35 @@ sorted(deps.to_list()) # recommended * Default: `false` +### String is no longer iterable + +When the flag is set to true, `string` objects are not treated as iterable. This +affects `for` loops and many functions, e.g. `list`, `tuple`, `min`, `max`, +`sorted`, `all`, and `any`. String iteration has been a source of errors and +confusion, such as this error: + +``` python +def my_macro(name, srcs): + for src in srcs: + # do something with src + +my_macro("foo") # equivalent to: my_macro(["f", "o", "o"]) +``` + +String indexing and `len` are still allowed. If you need to iterate over a +string, you may explicitly use: + +``` python +my_string="hello world" +for i in range(len(my_string)): + char = my_string[i] + # do something with char +``` + +* Flag: `--incompatible_string_is_not_iterable` +* Default: `false` + + ### Dictionary literal has no duplicates When the flag is set to true, duplicated keys are not allowed in the dictionary |