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I'm trying my hand at getting back into some C# coding and found that apparently the language now has var. My first thought was why would a professional, static

by jebblue 11y ago

I'm trying my hand at getting back into some C# coding and found that apparently the language now has var. My first thought was why would a professional, statically typed language have var. Checking out the page I linked to in the submission, you can also do this cool if not slightly funky looking thing where it looks like an SQL predicate just reading from an ordinary array.

nadams 11y ago
> My first thought was why would a professional, statically typed language have var. It might be because C++ has auto. Kind of related Java has Object. I haven't figured out if people want languages like C++ to be a loose typed language and just be able to type cast anything to a single type. Boost does introduce the variant type - but it's usage seems very unintuitive. I kind of get what they were trying to do - but overall Boost libraries seem overly complex for what they are trying to solve. I wrote my own variant type based on Ptype's variant [1] [2]. To me a variant shouldn't just be a container for any object - it should have some basic intelligence for built in types (like what to do when adding a string and an int - the result should be a string. Conversely - when adding an int and a string the result should be an int.). [1] https://srchub.org/p/cppvariant/source/tree/tip/variant.h https://srchub.org/p/cppvariant/source/tree/tip/variant.h [2] https://srchub.org/p/ptypes/source/tree/tip/src/pvariant.cxx https://srchub.org/p/ptypes/source/tree/tip/src/pvariant.cxx
louthy 11y ago
The 'cool but funky' thing is LINQ. Language Integrated Query. It can be used to query in-memory lists and arrays as well as build SQL to query a DB, or even query XML files. It is C#'s support for monads. In terms of var. It's best not to think of it as dynamic like javascript. You can't do this for example: var a = 123; a = "Hello"; The second line will throw an exception because 'a' is not a string, it's an int. So it's not dynamic like JS. It simply infers the type when it can so that you don't have to type it, otherwise its exactly the same. Interestingly C# does have a dynamic aspect too, and that's with the 'dynamic' keyword. dynamic x = 123; x = "Hello"; That will work where the var example wouldn't. It's a rarely used feature, but comes in useful to avoid boilerplate when dealing with external 'stuff', like XML files, JSON, or REST responses.

by jebblue 11y ago

nadams 11y ago

> My first thought was why would a professional, statically typed language have var. It might be because C++ has auto. Kind of related Java has Object. I haven't figured out if people want languages like C++ to be a loose typed language and just be able to type cast anything to a single type. Boost does introduce the variant type - but it's usage seems very unintuitive. I kind of get what they were trying to do - but overall Boost libraries seem overly complex for what they are trying to solve. I wrote my own variant type based on Ptype's variant [1] [2]. To me a variant shouldn't just be a container for any object - it should have some basic intelligence for built in types (like what to do when adding a string and an int - the result should be a string. Conversely - when adding an int and a string the result should be an int.). [1] https://srchub.org/p/cppvariant/source/tree/tip/variant.h https://srchub.org/p/cppvariant/source/tree/tip/variant.h [2] https://srchub.org/p/ptypes/source/tree/tip/src/pvariant.cxx https://srchub.org/p/ptypes/source/tree/tip/src/pvariant.cxx

louthy 11y ago

The 'cool but funky' thing is LINQ. Language Integrated Query. It can be used to query in-memory lists and arrays as well as build SQL to query a DB, or even query XML files. It is C#'s support for monads. In terms of var. It's best not to think of it as dynamic like javascript. You can't do this for example: var a = 123; a = "Hello"; The second line will throw an exception because 'a' is not a string, it's an int. So it's not dynamic like JS. It simply infers the type when it can so that you don't have to type it, otherwise its exactly the same. Interestingly C# does have a dynamic aspect too, and that's with the 'dynamic' keyword. dynamic x = 123; x = "Hello"; That will work where the var example wouldn't. It's a rarely used feature, but comes in useful to avoid boilerplate when dealing with external 'stuff', like XML files, JSON, or REST responses.