2018-01-10 6:19 GMT+03:00 Yegappan Lakshmanan <[email protected]>: > Hi Nikolay, > > On Tue, Jan 9, 2018 at 12:58 PM, Nikolay Aleksandrovich Pavlov > <[email protected]> wrote: >> 2018-01-09 18:59 GMT+03:00 Yegappan Lakshmanan <[email protected]>: >>> Hi Nikolay, >>> >>> On Mon, Jan 8, 2018 at 11:41 PM, Nikolay Aleksandrovich Pavlov >>> <[email protected]> wrote: >>>> 2018-01-08 9:23 GMT+03:00 Yegappan Lakshmanan <[email protected]>: >>>>> Hi, >>>>> >>>>> Which value you can use as the default value for a job >>>>> type variable? I see that there is a test_null_job() function >>>>> that returns a null job value (but it is supposed to be used >>>>> only for testing). But I don't see any other way to initialize >>>>> a variable to a null job value. Am I missing something? >>>> >>>> There is no such a thing as “abstract default value” in VimL, no >>>> matter the type; to define something like this language would need to >>>> have either constructions in which case return values of those >>>> constructors called without arguments may be named “default value for >>>> the type” (e.g. `list()` in Python returning empty list without >>>> arguments) or be typed without support for uninitialized variables >>>> (probably, only in part of the language) in which case whatever they >>>> are initialized to when not explicitly initialized define “default >>>> value for the type” (e.g. in C99 with `*tv = (typval_T) { .v_type = >>>> VAR_STRING }` everything, but `v_type` in `tv` becomes zero; another >>>> example is LabVIEW with “use default if unwired” terminals defaulting >>>> to false/empty array/etc). All other defaults come from code authors, >>>> for what you need to describe a task. >>>> >>>> So describe a task. >>>> >>> >>> I am creating a plugin that runs a command asynchronously. >>> This plugin supports only one asynchronous command at a time. >>> If the async command is already running, the plugin will stop the >>> current job and start a new job. >>> >>> I am using a variable to keep track of the current job. During the >>> plugin startup or when the job exits, I need to set this variable >>> to an empty or a sane value. Before starting a new job, I need to >>> compare this variable against some default value to check whether >>> a job is already running or not. As a workaround I am currently using >>> another variable to keep track of whether the job is running or not. >>> >>> We can use the following default values for other variable types: >>> Sting: "", Number: 0, List: [], Dict: {}. I am looking for some thing >>> similar for the Job variable. >> >> They are by no means default values, these are *empty* values, nothing >> more (see `:h empty()`, this applies to number too) >> > > How do we assign an empty value to a variable of Job type? > >> >> And VimL is not typed, you *don’t* need what you are asking for: >> just initialize variable to zero and check with `if var is 0`, this will >> yield >> false if `var` happens to have type other then Number or value other >> then zero. >> > > Yes. I can use "is" to check whether var is set to 0. But this looks like > a workaround. I was looking for a way to initialize the variable to > an empty Job value. I will go with the "is" check for now.
It is not a workaround, it is how things are normally done in a dynamically typed language, especially when there is no JIT which does type guessing and may get distracted by poor choice of default value. Would do the same thing in Python using None. > > Thanks, > Yegappan > > -- > -- > You received this message from the "vim_dev" maillist. > Do not top-post! Type your reply below the text you are replying to. > For more information, visit http://www.vim.org/maillist.php > > --- > You received this message because you are subscribed to the Google Groups > "vim_dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. -- -- You received this message from the "vim_dev" maillist. Do not top-post! Type your reply below the text you are replying to. For more information, visit http://www.vim.org/maillist.php --- You received this message because you are subscribed to the Google Groups "vim_dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
