crystal-lang/crystal

The Crystal programming language | http://crystal-lang.org | Fund Crystal's development: http://is.gd/X7PRtI | Docs: http://crystal-lang.org/docs/ | API: http://crystal-lang.org/api/

didactic-drunk

@didactic-drunk

@what for the caller?

George Dietrich

@Blacksmoke16

is Class::Name the same as the class the method is in?

didactic-drunk

@didactic-drunk

First example didn't quiet work

class Foo
  macro foo
    p "{{"#{@type.name.id}.#{@def.name.id}".id}}"
  end
end

class Bar
  def bar
    Foo.foo
  end
end

Bar.new.bar => "Foo.bar"
# Should print "Bar.bar"

George Dietrich

@Blacksmoke16

https://play.crystal-lang.org/#/r/bhl6

didactic-drunk

@didactic-drunk

My more complex code shows Foo.bar

George Dietrich

@Blacksmoke16

got a link?

didactic-drunk

@didactic-drunk

Not published, I'll work on it

George Dietrich

@Blacksmoke16

the \{{ is impt

otherwise the macro expression is evaluated within the macro def

Ramakrishnan Vasantha Gopal

@vgramkris

hey, new here, posting some general questions out here.
Any reason why String.to_i32! is not implemented?

a : Int64 = (Int32::MAX).to_i64 + 1
b : Int32 | Nil = a.to_i32!
c : String = a.to_s
d : Int32 | Nil = c.to_i32!  # Error: undefined method 'to_i32!' for String

George Dietrich

@Blacksmoke16

what would to_i32! to diff than .to_i32?

do diff*

Ramakrishnan Vasantha Gopal

@vgramkris

if you see above, in line 2, assignment to be works fine

but line 4 is an issue

George Dietrich

@Blacksmoke16

right, can't you just call c.to_i32?

Ramakrishnan Vasantha Gopal

@vgramkris

so if the String cannot be typecasted to i32 then i expect nil instead of a exception

George Dietrich

@Blacksmoke16

it'll raise on over/under flow iirc

Ramakrishnan Vasantha Gopal

@vgramkris

thats right, that is what i am trying to overcome with the '!'

George Dietrich

@Blacksmoke16

you're getting a compile time error not an over/underflow exception

if you want it to wrap, try .to_i32?

Ramakrishnan Vasantha Gopal

@vgramkris

yep thats right

George Dietrich

@Blacksmoke16

so im not sure i see the problem?

going from a number to number has diff semantics than a string to a number, which is probably why they have slightly diff conversion methods

Ramakrishnan Vasantha Gopal

@vgramkris

yeah exactly, so num to num with ! we can do both checking & assignment in same line

but from string to num i need to check with .to_i32? and then assign

that is what i was trying to understand if there is any reason why for string they did not have .to_i32! while they do have .to_i32 for string

George Dietrich

@Blacksmoke16

still not sure i follow, you deff can do like d : Int32 | Nil = c.to_i32?

because to_i32! represents a wrapping operation on the value if it over/underflows. In the case of a string its to_i32? because you cant wrap a string, and needs to handle the case of the string not being a number. So it'll return nil if either of those happen

Ramakrishnan Vasantha Gopal

@vgramkris

okay this makes sense.. thanks!

George Dietrich

@Blacksmoke16

there is a block version of to_i32 that you can use. Which will use the blocks value in case of under/overflow or its not a valid number

e.g. e : Int32 = c.to_i { 0 }

habit, to_i is the same as to_i32

Ramakrishnan Vasantha Gopal

@vgramkris

sure, this would work as well! thanks @Blacksmoke16

George Dietrich

@Blacksmoke16

np, ofc another solution is to just not go from number to string to number :)

but i assume that was just an example

Ramakrishnan Vasantha Gopal

@vgramkris

baiorett

@baiorett

hi, quick question: how do i split crystal classes to multiple files

George Dietrich

@Blacksmoke16

for what reason?

Daniel Worrall

@Daniel-Worrall

Just define them in multiple files.

You can reopen classes

George Dietrich

@Blacksmoke16

but to answer your question just declare the class and add more stuff to ^

re-declare

Daniel Worrall

@Daniel-Worrall

If you're overwriting methods in the same class, require order matters

baiorett

@baiorett

alright thank you

George Dietrich

@Blacksmoke16

i'd suggest thinking if you really want to do that tho. could just make things more confusing

baiorett

@baiorett

im sorta used to splitting classes because i came to crystal from java

George Dietrich

@Blacksmoke16

Other people might not be. Especially if it's a small type

Depends on the exact use case tho. Not going to really harm anything, but is possible it might mess with overload order

baiorett

@baiorett

Depends on the exact use case tho. i don’t think i’m really going to split each class and make tons of class-files

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