The Dot and Variables
What does the dot do in the templates
Preface
All available data that can be used in YAGPDB's templating "engine" which is slightly modified version of Golang's stdlib text/template package; more in depth and info about actions, pipelines and global functions like printf, index, len,etc > https://golang.org/pkg/text/template/
At current state this is still prone to formatting errors, but everything in a code block should refer to a function, parts of a template's action-structure or output returned by YAGPDB; single word/literal-structure in italics refers to type. Methods and fields (e.g. .Append, .User) are usually kept in standard formatting. If argument for a function is optional, it's enclosed in parenthesis ( ). If there are many optional arguments possible, it's usually denoted by 3-dot ...ellipsis.
Always put curly brackets around the data and "actions you perform" you want to formulate as a template's action-structure like this: {{.User.Username}}
This {{ ... }} syntax of having two curly brackets aka braces around context is always necessary to form a template's control structure aka an action with methods and functions stated below.
The Dot and Variables
The dot {{ . }} encompasses all active data available for use in the templating system, in other words it always refers to current context.
From official docs > "Execution of the template walks the structure and sets the cursor, represented by a period . and called "dot", to the value at the current location in the structure as execution proceeds." All following fields/methods/objects like User/Guild/Member/Channel etc are all part of that dot-structure and there are some more in tables below.
$ has a special significance in templates, it is set to the starting value of a dot. This means you have access to the global context from anywhere - e.g., inside range/with actions. $ for global context would cease to work if you redefine it inside template, to recover it {{ $ := . }}.
$ also denotes the beginning of a variable, which maybe be initialized inside a template action. So data passed around template pipeline can be initialized using syntax > $variable := value. Previously declared variable can also be assigned with new data > $variable = value, it has to have a white-space before it or control panel will error out. Variable scope extends to the end action of the control structure (if, with, or range) in which it is declared, or to the end of custom command if there are no control structures - call it global scope.
Trying what you think of is the best approach to learning codes. Before asking any question, you should try it first.
Pipes
A powerful component of templates is the ability to stack actions - like function calls, together - chaining one after another. This is done by using pipes |. Borrowed from Unix pipes, the concept is simple: each pipeline’s output becomes the input of the following pipe. One limitation of the pipes is that they can only work with a single value and that value becomes the last parameter of the next pipeline.
Example: {{randInt 41 | add 2}} would pipelinerandInt function's return to addition add as second parameter and it would be added to 2; this more simplified would be like {{40 | add 2}} with return 42. If written normally, it would be {{ add 2 (randInt 41) }}. Same pipeline but using a variable is also useful one -{{$x:=40 | add 2}} would not return anything as printout, 40 still goes through pipeline to addition and 42 is stored to variable $x.
Pipes are useful in select cases to shorten code and in some cases improve readability, but they should not be overused. In most cases, pipes are unnecessary and cause a dip in readability that helps nobody.
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