On 3/6/22 5:49 AM, Bram Moolenaar wrote:
Yes, that is the problem we need to tackle. Considering the above, how
about introducing different null types:
null_string
null_dict
null_list
null_function
null_partial
null_channel
null_job
That will allow for clearing a script-local variable, while keeping the
type. And it allows for using a null value in a dict or list while
keeping the type.
This scheme certainly satisfies my requirements. One question, there's
if jobs.write != null_job
but what about
var sval = ''
if sval == null_string
is this true or false? Or is string a special case and you need
if sval is null_string
Requiring 'is' is confusing
-ernie
Another example, consider preparing a list with jobs, but the jobs have
not been created yet:
var jobs = {read: null_job, write: null_job, check: null_job}
...
jobs.read = job_start(...)
if writing
jobs.write = job_start(...)
endif
jobs.check = job_start(...)
...
if jobs.write != null_job
# write
endif
This looks better than just using "null" and handling the type
difference in some way.
Another problem not mentioned yet: When using a default value for a
function argument, and the type is channel, there was no value that
could be used. null_channel would be useful there too.
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