gross-store: exemplar uses unknown syntax

[ErikSchierboom]

The gross-store exercise's exemplar solution uses a concepts that is not in the prerequisites:

if _, ok := units[unit]; !ok {

I don't know what to do with this: rewriting the code or explaining what the if ...; .. syntax does.

[iHiD]

@junedev Thoughts on this?

[junedev]

This syntax is used rather frequently and although it is sometimes overused in other cases, it is idiomatic in this use case. This syntax should be introduced as part of the conditionals-if concept (cars assemble).

[ErikSchierboom]

@junedev The cars-assemble exercise does not know about multiple return values, so I felt like teaching the natural place to introduce this syntax is in the exercise that will teach multiple return values: card-tricks: #1619 The gross-store exercise can then have multiple-return-values as a prerequisite.

[junedev]

@ErikSchierboom You are totally right, multiple return values are not introduced yet. However multiple return values have no actual relation to the if expression; condition { ... } syntax. Imagine this code for example:

if num := someFunction(); num != 0 {
  //...
}

So feel free to ignore this, but I still think if expression; condition { ... } should be part of conditionals-if and additionally we need to find a home for introducing multiple return values. Why do you think it fits with Card Tricks?

Why not adding it to Gross Store where we need it? Is that "too late" in the tree?

[ErikSchierboom]

@junedev Issue created: #1644

[ErikSchierboom]

additionally we need to find a home for introducing multiple return values. Why do you think it fits with Card Tricks?

Well, card-tricks uses multiple return values (func GetItem(slice []uint8, index int) (uint8, bool)) and the introduction is relatively short, so I felt it there was room there.

[junedev]

Ah, I missed that part when skimming the file. All good then.