V2 - Map Lookup Fallback / Test + Lookup

[Coiler]

Currently, one needs to use my_map.Has(key) if the programmer is unsure of a key being in the map or not. However, I'm pretty sure the internal code for Has() most likely needs to do a full key search to return the answer. And almost certainly, the programmer is going to have code that looks like this:

Code: Select all

if( my_map.Has(my_key) )
	my_var := my_map[my_key]

This means the lookup is done twice for every lookup, when uncertain. I propose a new ability to safely scope out map elements and obtain their value at the same time when they exist. If I were developing the system, I would also add (any/all of) the following features to map objects:

• A safe map.Get(my_key,my_default) function that returns the user's default value when the key doesn't exist.
• A map.SetIfMissing(my_key,my_value) type function that only assigns the value if the key doesn't exist (probably with a better function name).
• A map.GetSet(my_key,start_value) type function that assigns start_value only when the key doesn't exist, then returns the current key value afterward.

Thanks for reading my wishes!

[HotKeyIt]

You can use try

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my_key:="anykey"
my_map:=Map()
try my_var := my_map[my_key]
catch
  my_var:="default"
MsgBox my_var

In AutoHotkey_H you can use DefineDefault:

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my_key:="anykey"
my_map:=Map().DefineDefault("default")
my_var := my_map[my_key]
MsgBox my_var

[nnnik]

Using try is really an antipattern in this case.
I would suggest the following function names (taken from https://docs.oracle.com/javase/8/docs/api/java/util/Map.html)
map.Get(my_key,my_default)->map.getOrDefault(my_key,my_default)
map.SetIfMissing(my_key,my_value)->map.computeIfMissing(my_key, callable)

Also I don't think a map needs to throw if an entry is accessed that is missing.
Neither Java nor javascript throw if an entry is accessed that doesn't exist.
Weirdly Python does throw if you use the [] syntax but doesn't throw if you use get.
Perhaps instead of addig these weird workarounds we should add an access method that doesn't throw.