I was reading a text in which the author used "call into" when explaining Templated Razor Delegates within the following sentence:

Note that the delegate that’s generated is a Func. Also, the @item parameter is a special magic parameter. These delegates are only allowed one such parameter, but the template can call into that parameter as many times as it needs.

I am wondering what "call into" means here and what would the difference be if he used "call" instead.

I've done a small research and I found this in which it says "call into" means "to call to a person or a pet to come into something or some place." and well, it doesn't make much sense in this context I believe.

Note the complete text can be found here at: http://haacked.com/archive/2011/02/27/templated-razor-delegates.aspx

  • I would say "use" in place of "call into". Don't expect writer-grade English from a blog by a programmer. – user16269 Oct 15 '12 at 3:12
  • I don't but does it feel right to you? – Tarik Oct 15 '12 at 3:39
  • Technically a template doesn't call or call into anything. Instead a pre-processor replaces template macros with whatever required end result. The writer is probably using the term loosely to draw a picture of multiple visits to whatever the list holds. It's a useful mental picture for using the feature however, as i've stated, templates never call anything. – Chris Oct 15 '12 at 3:48
  • @DavidWallace: I think the writer is trying to mimic the calling term, commonly used in programming languages. – Noah Oct 15 '12 at 4:01
  • I think that this is an erroneous conflation of call and tap into. It happens ... | Marking as 'too localised' as this question is unlikely to be of help to anybody else. – coleopterist Oct 15 '12 at 6:20

"Call into" in this context is referring to the process of entering a programmatic sub-routine or function. In imperative software development, a function is a section of code which encapsulates some piece of functionality that is likely to be used repeatedly. It is named, and may have input and output values (or may have none, and just carry out some side-effect internally).

You would then use this function to carry out the piece of work multiple times, which is referred to as "calling into the function".

A couple of people have claimed that 'call into' isn't relevant for the use of templates, where an identifier may be expanded and replaced with some piece of pre-defined template multiple times. Whilst not technically 'calling into' the template, the effect is similar - i.e., repeating an action which has been previously defined - so colloquialisms and shorthand mean that many people use the same term to refer to both.


A delegate in this context is effectively a placeholder for a function/method, or a section of code that can be called by the template. It's not known in advance what this function will be except that there will be one, even if it does nothing when it is invoked.

According to the Microsoft Style Guide, you 'call the referenced method' in a delegate rather than 'call into' one. There is no difference in meaning. I think Phil said 'call into' because the delegate method is 'passed into' the template as a parameter, but the two are synonymous.

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