All,
I wrote a macro which allows for using a pattern to essentially extract a
value from a data structure:
@doc """
Filter a value out of data using a pattern with one variable. Returns a
default value
if no match. Raises if pattern contains no variables or more than one
variable.
## Examples
iex> "$3.45" |> PatternHelpers.pattern_filter("$" <> money) |>
String.to_float()
3.45
iex> {1,2,3} |> PatternHelpers.pattern_filter({1,_,a})
3
iex> %{a: 1, b: 2} |> PatternHelpers.pattern_filter(%{a: 9, b: b})
nil
iex> %{a: 1, b: 2} |> PatternHelpers.pattern_filter(%{a: 9, b: b}, "???")
"???"
"""
And an unsafe version:
@doc """
See `pattern_filter/3`. Raises if no match.
## Examples
iex> {1,2,3} |> PatternHelpers.pattern_filter!({9,_,b})
** (MatchError) no match of right hand side value: {1, 2, 3}
"""
This is my first proposal. Please let me know if this idea is worth some
attention, and how I might better do my part to present it. I have code
obviously but I'm not sure this is the place for it.
Thanks,
Matt F
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