From a9886bf2f8a35369a2c42070c5f83504dfab2bc5 Mon Sep 17 00:00:00 2001
From: Jasper Ras <jras@hostnet.nl>
Date: Fri, 27 Jun 2025 10:56:03 +0200
Subject: vault backup: 2025-06-27 10:56:02

---
 Golang.md | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 55 insertions(+), 1 deletion(-)

(limited to 'Golang.md')

diff --git a/Golang.md b/Golang.md
index 3b3438f..ea9dfcd 100644
--- a/Golang.md
+++ b/Golang.md
@@ -1 +1,55 @@
-[[What are Type Assertions in Go and when to use them]]
\ No newline at end of file
+[[What are Type Assertions in Go and when to use them]]
+
+# TODO
+make a note about :
+statement -> expression -> declaration, etc. Idea: draw it in some way, making it visual might help remembering.
+# DIGEST INTO NOTES
+Slices are dynamically sized arrays that can be accessed `s[i]` or a subset can be taken `s[i:j]`. Indexing: half-open (starts at 0). `s[i:j]` yields  i through j-1. Either can be omitted.
+
+Convention: comment describing package preceding package declaration.
+
+Variables initialised to "zero value".7689
+String concatenation via `+` char.
+Supports assignment operators, e.g `+=`, `*=` etc
+Short-hand variable declaration requires no type, it is inferred of the value `:=` **only allowed in a function**
+
+For-loop structure:
+```
+for initialization; condition; post {
+	// code
+}
+```
+Either part can be left away with different semantics. 
+All parts gone: loop forever.
+Only condition is like a while x == true;
+`range` keyword to loop over a slice or array with `for index, arg := range slice`
+
+`_` is the blank identifier, thus above if we don' need the index we can put `_`.
+
+---
+
+`image/color` package features the Color interface defining a Color as just a type that has a method `RGBA() (r, g, b, a uint32)`. It has a struct `RGBA` defining this method. So for example to define green we can say: `color.RGBA{0x00, 0xFF, 0x00, 0xFF}` R G B A respectively.
+
+Packaging doing stuff with networking are grouped under `net`, e.g `net/http`
+
+Using `io.Copy` we can copy output from a reader to a writer. This way we can for example copy a HTTP response directly to stdout instead of buffering the entire output first.
+
+`strings.HasPrefix` exists
+
+To get a time delta we can use `time.Since` which returns a `time.Time`. We can just call for example `Seconds()` on that to get the elapsed seconds.
+
+Goroutines run concurrently and communicate over channels, they are started with the `go` keyword. Sending or receiving on a channel block the goroutine.
+
+---
+ 
+Order of map iteration is unspecified but random in practice to prevent reliance on ordering.
+The Scanner type from the bufio package provides an easy way to read input in lines or words.
+Map created with `make` is passed by reference.
+Package `io/ioutil` exposes `ReadFile` and other io utility functions and types.
+Casting works by `type(var)`, e.g `i := 0; string(i)`
+Referencing a multi-component package is done through the last component. E.g `ioutil` for the `io/ioutil` package.
+Composite literals are the form of `type{...}` they instantiate composite types, so `[]string{"a"}` is also a composite literal.
+
+---
+
+Gin bool required bind fails if false, needs ptr to bool. https://github.com/gin-gonic/gin/issues/814
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