bump.lua - minimal collision detection lib

[dreadkillz]

Yes, it's passing a string to "string.format"; every string has a metatable with the field __index similar to this:

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function(t, i) return string[i] end

Got it. I need to learn about these fancy metamethods.

[kikito]

@ishkabible: I think I've found the issue - it was related with the way I calculated the friction (which is not part of the lib). I updated the demo. Please try it again.

So for the above code, you are passing ("coins: %d") to format?

In case it's not clear, these two are equivalent:

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("coins: %d"):format(player.coins)
string.format("coins: %d", player.coins)

Notice that you have to put parenthesis around the string to use the first notation. Otherwise (if you print "coins: %d":format(...) ) the Lua parser "complains".

[Zeliarden]

I think I've found the issue

That was it for me too. Works fine now

[ishkabible]

kikito: it's fixed

I've always disliked how Lua handles that bit of syntax. variables, table constructors, strings, numbers, nil, true, false, etc... should all be treated the same by the parser but alas, Lua decided to give a bit of special syntax to variables and () :/

also the speceil function call syntax only allows for strings and table constructors when it should allow for variables, numbers, nil, true, false, etc...

Lua's idea of a primary expression is strange.

[bartbes]

The parentheses are merely for grouping, it's just a limitation of the parser. That said, everything is treated the same, (table):method() works too, and the colon syntax works for every kind of variable. Now, what you are mistaken not being able to use it for, is not being able to set a metatable. (So (3):something() could work, but since you can't set a metatable, you can't tell it where to look.)

[munchor]

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Error: main.lua:35: attempt to call field 'check' (a nil value)
stack traceback:
	main.lua:35: in function 'update'
	[string "boot.lua"]:407: in function <[string "boot.lua"]:373>
	[C]: in function 'xpcall'

I'm getting that error with the demo.

[kikito]

I'm getting that error with the demo.

You probably have an old demo. Try downloading it again.

[munchor]

I got mine from github :S

[kikito]

Mm. I think I know what happened. You downloaded the master branch, where I had left an old main.lua file by mistake. Sorry for having confused you. I've removed that file now.

The master branch only has the bump.lua file, the README and the license. The demo is on a different branch, called "demo", and it has more files. You can see them via the "branch" dropdown in the github page.

Or you can download the .love file of the demo directly from the downloads section - the file there should always be up to date.

If you have cloned the repo, you can see the demo branch by doing this inside the repo folder:

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git checkout -b demo origin/demo

From that moment on, you can switch back to the master branch doing

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git checkout master

And to see the demo again:

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git checkout demo

[munchor]

Thank you! This time it worked perfectly