Thank you Mark. I followed that explanation and now understand that -
for all of my foreseeable applications - I can ignore 'is strictly a
name' :-)
Paul
On 9/1/2023 1:23 PM, Mark Waddingham via use-livecode wrote:
On 2023-09-01 17:44, Paul Dupuis via use-livecode wrote:
I may just be experiencing a brain fart, but I have read the release
notes several times, and I don't understand the purpose of the new:
is strictly a name
operator? Can someone explain its purpose in really basic terms or
examples?
Its purposes is so that it is possible to tell when a value is a
'name' rather than a 'string' when the distinction is important. The
cases where this is true are few and far between - indeed, the
use-case it was added for was so that the exact runtime type of
constant values generated when parsing script (e.g. from constant
initializers) is preserved.
There are two kinds of strings internally - strings and names. All
names are strings, but not all strings are names.
The difference is that there is only ever one instance of a name with
a given string in memory - e.g. if two variables hold a name whose
string is "foo", then they will hold the same pointer.
As to what names are - they are an optimization for cases where the
engine will often do comparisons between them.
Names are implemented in a global hash table in such a way that
caseless and case-sensitive comparisons are constant time (when both
values being compared are names).
The keys of an array are names - which means the engine never has to
compare the actual characters of a key in an array as it does a lookup.
Literals in scripts are stored as names - so if you have 100 instances
of the string constant "foobar" throughout all your scripts as
literals - there will only actually be one instance of "foobar"
Similarly, internally, object names, handler names and variable names
are all stored as, well, names (again - because they are commonly
compared against each other).
Some examples of where you can observe a name are:
put "foo" is strictly a name => true
put ("foo" & empty) is strictly a name => false
repeat for each key tFoo in { "foo": true }
put tFoo is a strictly a name => true
end repeat
There might be a few other places where you could see a name rather
than a string, but as mentioned above - its unlikely that 99.9% of
people would ever need to worry about it :)
Warmest Regards,
Mark.
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