Make polars.Expr.str.replace and polars.Series.str.replace default to similar behavior of built python and rust replace methods

[mesner]

Make polars.Expr.str.replace and polars.Series.str.replace default to similar behavior of built python and rust replace methods

[JulianCologne]

100 % agree that this is unexpected and fell in this trap before 😨

• python: "hiiiii".replace("i", "X") -> "hXXXXX"
• rust: "hiiiii".replace("i", "X") -> "hXXXXX"
• polars: pl.lit("hiiiii").str.replace("i", "X") -> "hXiiii"

while on the topic 2 more things

remove replace_all

is this not redundant and can currently be achieved with replace and n=-1 (should be default imo) ??

make regex "opt-in" (will create another issue to discuss)

imo regex should be "opt-in" (regex=False by default; currently literal=False)

This caused multiple problems already because this also unexpected and can happend quite fast

• pl.select(pl.lit("hiiiii").str.replace(".", "X")) -> "Xiiiii" (expected nothing to change)

[cmdlineluser]

I wasn't actually aware that n=-1 would replace all instances (doesn't seem to be mentioned in the docs):

pl.select(pl.lit("foooooo").str.replace("o", "e", n=-1))
# shape: (1, 1)
# ┌─────────┐
# │ literal │
# │ ---     │
# │ str     │
# ╞═════════╡
# │ feeeeee │
# └─────────┘

There is also a separate .replace_all() function.