My understanding is that inside of a coffeescript function, "this" or "#" is equal to "window" (at least in the context of Rails). Why is it then that I can get this code to work:
window.googletag = window.googletag or {}
window.googletag.cmd = window.googletag.cmd or []
window.googletag.cmd.push ->
window.googletag.defineSlot('/1003175/ad-name-here', [336, 280], 'div-gpt-ad-1349373630997-0').addService(window.googletag.pubads())
window.googletag.pubads().enableSingleRequest()
window.googletag.enableServices()
but not this code
#googletag = #googletag or {}
#googletag.cmd = #googletag.cmd or []
#googletag.cmd.push ->
#googletag.defineSlot('/1003175/ad-name-here', [336, 280], 'div-gpt-ad-1349373630997-0').addService(#googletag.pubads())
#googletag.pubads().enableSingleRequest()
#googletag.enableServices()
When I place in my code alert(# == window) I get true.. if they are the same then why would one work but not the other? Is there not a more graceful way to write this code then appending window to every instance of the word googletag?
In coffeescript, the # is equivalent to this, but the value of this is dependent on your current scope within the code. In your example, alert(# == window) returns true because in that context this is the window. But when you use it in another context, for example inside a function definition (#googletag.cmd.push -> ...) then it will get the context of whatever scope that function is called from.
In the end this is not a coffeescript issue but a Javascript issue. I'd recommend reading up a bit more on this, it's a somewhat confusing concept at first.
Here's one article that helped me understand the concept better: http://yehudakatz.com/2011/08/11/understanding-javascript-function-invocation-and-this/
Related
I have an SVG object like that:
<svg class="class-a color-green marker" .../>
In Playwright I want to get an exact list of classes of this element. I use the following code to locate it:
page.locator(".status-marker").first
The node is located properly, but when I call evaluate("node => node.className") on it, I get an empty dict, like the locator stripped all information about classes at all.
In general, it doesn't matter how I get the handle of this element, I always get an empty dict on evaluate("node => node.className").
Calling page.locator(".status-marker").first.is_visible() returns True, so the object exists.
Also if I run page.locator(".status-marker").first.evaluate("node => node.outerHTML") I'll get the full HTML of that node, that does have the class name included. I could parse that, but it would be pretty clunky solution.
I found out that I could use expect(locator).to_have_class(), but If the node has more than one class I need to put all of them for it to pass, when I care only on one of them (the other classes are dynamically generated, so I can't even know about them during tests).
Edit:
Here's some additional sample:
assert page.locator(".marker").first.evaluate("node => node.className") == {}
expect(page.locator(".marker").first).to_have_class("text-green-1")
The first assert passes - the evaluate("node => node.className") returns an empty dict. The expect() fails with the following error:
AssertionError: Locator expected to have class 'text-green-1'
E Actual value: inline pr-2 text-green-1 marker svelte-fa s-z-WEjw8Gh1FG
I've found a way to reproduce it (it happens to me in font awesome plugin for svelte):
def test_svelte_fa(page):
page.goto("https://cweili.github.io/svelte-fa/")
item = page.locator(".svelte-fa").first
assert item.is_visible()
assert "svelte-fa" in item.evaluate("node => node.className")
In your example, the className of an SVG is an SVGAnimatedString object. Which is not serializable.
If you do JSON.stringify($('.svelte-fa').className) on the browser, you will see that the value is {}.
Values returned by the evaluate function needs to be serializable.
I have a Lua function where I build a table of value and attempt to add it to a global table with a named key.
The key name is pulled from the function arguments. Basically, it's a filename, and I'm pairing it up with data about the file.
Unfortunately, the global table always comes back nil. Here's my code: (let me know if you need to see more)
(Commented parts are other attempts, although many attempts have been deleted already)
Animator = Class{}
function Animator:init(atlasfile, stringatlasfriendlyname, totalanimationstates, numberofframesperstate, booleanstatictilesize)
-- Define the Animator's operation mode. Either static tile size or variable.
if booleanstatictilesize ~= false then
self.isTileSizeStatic = true
else
self.isTileSizeStatic = false
end
-- Define the total animation states (walking left, walking right, up down, etc.)
-- And then the total frames per state.
self.numAnimationStates = totalanimationstates or 1
self.numAnimationFrames = numberofframesperstate or 2
-- Assign the actual atlas file and give it a programmer-friendly name.
self.atlasname = stringatlasfriendlyname or removeFileExtension(atlasfile, 'animation')
generateAnimationQuads(atlasfile, self.atlasname, self.numAnimationStates, self.numAnimationFrames)
end
function generateAnimationQuads(atlasfile, atlasfriendlyname, states, frames)
spriteWidthDivider = atlasfile:getWidth() / frames
spriteHeightDivider = atlasfile:getHeight() / states
animationQuadArray = generateQuads(atlasfile, spriteWidthDivider, spriteHeightDivider)
animationSetValues = {atlasarray = animationQuadArray, width = spriteWidthDivider, height = spriteHeightDivider}
--gAnimationSets[#gAnimationSets+1] = atlasfriendlyname
gAnimationSets[atlasfriendlyname] = animationSetValues
--table.insert(gAnimationSets, atlasfriendlyname)
end
Note: when using print(atlasfriendlyname) and print(animationSetValues), neither are empty or nil. They both contain values.
For some reason, the line(s) that assign the key pair to gAnimationSets does not work.
gAnimationSets is defined a single time at the top of the program in main.lua, using
gAnimationSets = {}
Animator class is called during the init() function of a character class called Bug. And the Bug class is initialized in the init() function of StartState, which extends from BaseState, which simply defines dummy init(), enter(), update() etc. functions.
StartState is invoked in main.lua using the StateMachine class, where it is passed into StateMachine as a value of a global table declared in main.lua.
gAnimationSets is declared after the table of states and before invoking the state.
This is using the Love2D engine.
Sorry that I came here for help, I've been picking away at this for hours.
Edit: more testing.
Trying to print the animationQuadArray at the index gTextures['buganimation'] always returns nil. Huh?
Here's gTextures in Main.lua
gTextures = {
['background'] = love.graphics.newImage('graphics/background.png'),
['main'] = love.graphics.newImage('graphics/breakout.png'),
['arrows'] = love.graphics.newImage('graphics/arrows.png'),
['hearts'] = love.graphics.newImage('graphics/hearts.png'),
['particle'] = love.graphics.newImage('graphics/particle.png'),
['buganimation'] = love.graphics.newImage('graphics/buganimation.png')
}
Attempting to return gTextures['buganimation'] returns a file value as normal. It's not empty.
My brain is so fried right now I can't even remember why I came to edit this. I can't remember.
Global table in Main.lua, all other functions can't access it.
print(gTextures['buganimation']) works inside the function in question. So gTextures is absolutely accessible.
Table isn't empty. AnimationSetValues is not empty.
I'm adding second answer because both are correct in context.
I ended up switching IDE's to VS Code and now the original one works.
I was originally using Eclipse LDT with a Love2D interpreter and in that environment, my original answer is correct, but in VS Code, the original is also correct.
So Dimitry was right, they are equivalent, but something about my actual Eclipse setup was not allowing that syntax to work.
I switched to VS Code after I had another strange syntax problem with the interpreter where goto syntax was not recognized and gave a persistent error. The interpreter thought goto was the name of a variable.
So I switched, and now both things are fixed. I guess I just won't use LDT for now.
Solution: Lua syntax. Brain Fry Syndrome
I wrote:
animationSetValues = {atlasarray = animationQuadArray, width = spriteWidthDivider, height = spriteHeightDivider}
Should be:
animationSetValues = {['atlasfile']=atlasfile, ['atlasarray']=animationQuadArray, ['width']=spriteWidthDivider, ['height']=spriteHeightDivider}
Edit: I'm fully aware of how to use answers. This was posted here to reserve my spot for an answer so I could edit it later when I returned back home, which is exactly what I'm doing right now. I'll keep the old post for archival purposes.
Original:
I solved it. I apologize for not posting the solution right now. My brain is melted into gravy.
I will post it tomorrow. Just wanted to "answer" saying no need to help. Solved it.
Solution is basically, "oh it's just one of those Lua things". Wonderful. I'm having so much fun with this language - you can tell by my blank expression.
From the language without line endings or brackets, but forced print parentheses... ugh. I'm going back to C# when this class is done.
Actually I am writting a programming language in Lua. It was quite fun. I've wrote a bit of standard library (stack op and simple io). Then I've thought about labels. It would look like in assembly. While and for loop aren't funny in any bit so programming in that language can be quite challenging. Here are some requirements for this system:
Label stack (or array, dictionary) must be accessible from global context.
Jump instruction handler will be in separate file.
This is how my label-handling function look like:
function handleLabel(name,currentLine)
end
I have no idea how to implement this kind of magic. First I've thought about that:
LabelLineIDS = {}
Labels = {}
Labelamount = 1;
function handleLabel(name,currentLine)
LabelLineIDS[Labelamount]=currentline
Labels[Labelamount]=name
Labelamount=Labelamount+1
end
-- In file "jump.lua":
local function has_value (tab, val)
for index, value in ipairs(tab) do
if value == val then
return index
end
end
print ("Error: Label not defined.") -- Bail out.
os.exit(1)
end
local function _onlabel()
local labelName = globalparams --Globalparams variable contain parameters to each function, at the moment
--this will contain label name. It _can_ be nil.
return LabelLineIDS[has_value(Labels, labelName)]
end
CurrLine = _onlabel() --Currline - current line that get's parsed.
--1 command per one line.
But I'm unsure is this well written or even work. Can you give me idea how to parse labels in my programming language (and write jump functions)? Or if my code is pretty ok at the moment, can you help me to improve it?
Using line counter in my parser I've decided to implement gotos like we can see in BASIC. Thanks everyone for help.
I would like to create a keybinding to switch focus to the master client. Profjim on this forum thread notes:
To get the master client on the current tag:
c = awful.client.getmaster()
I have tried the following, but it causes my ~/.config/rc.lua file to be ignored, which is the behavior if there is an error in the file. Does anyone know the correct syntax?
awful.key({ modkey, , "e", awful.client.getMaster()),
Note: "e" shouldn't cause any conflicts if you have the default key bindings.
Edit: Someone on /r/awesomewm knew the syntax to solve my problem:
awful.key({ modkey, }, "e", function() client.focus = awful.client.getmaster(); client.focus:raise() end),
Lets start with the syntax errors; from the documentation it seems that awful.key is a table, not a function. and it would presumably contain keys...which are hash tables, not sequences.
Finally your table syntax is wrong; a field may not be syntactically empty, it must have a listed value, even if that value is nil.
So basically you are trying to pass the wrong kind of value to something that can't be called.
As for how to do it correctly...the documentation is confusing, and apparently I'm not the only one that thinks so.
*deep breath*
okay, awful.new(...) creates key binders(?), and awful.key contains key bindings, so clearly we have to put the results of the first into the second.
the code on your link is but a pointer, and only covers focusing the window, not creating a keybinding.
It seems like you want something like this:
function do_focus()
current = client.focus
master = awful.client.getmaster()
if current then
client.focus = master
master:raise()
end
end
table.insert(awful.key, awful.new (modkey, 'e', nil, do_focus) )
Bare in mind that I have no way of testing the above code.
I'm trying to get a handle on how OOP is done in Lua, and I thought I had a simple way to do it but it isn't working and I'm just not seeing the reason. Here's what I'm trying:
Person = { };
function Person:newPerson(inName)
print(inName);
p = { };
p.myName = inName;
function p:sayHello()
print ("Hello, my name is " .. self.myName);
end
return p;
end
Frank = Person.newPerson("Frank");
Frank:sayHello();
FYI, I'm working with the Corona SDK, although I am assuming that doesn't make a difference (except that's where print() comes from I believe). In any case, the part that's killing me is that inName is nil as reported by print(inName)... therefore, myName is obviously set to nil so calls to sayHello() fail (although they work fine if I hardcode a value for myName, which leads me to think the basic structure I'm trying is sound, but I've got to be missing something simple). It looks, as far as I can tell, like the value of inName is not being set when newPerson() is called, but I can't for the life of me figure out why; I don't see why it's not just like any other function call.
Any help would be appreciated. Thanks!
Remember that this:
function Person:newPerson(inName)
Is equivalent to this:
function Person.newPerson(self, inName)
Therefore, when you do this:
Person.newPerson("Frank");
You are passing one parameter to a function that expects two. You probably don't want newPerson to be created with :.
Try
Frank = Person:newPerson("Frank");