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kotlinlang

Is this syntax is correct,
`model?.let{ some code} ?: run { code in case model is null}`

syntactically correct but IMO just wrong in terms of style, you probably looking for if/else:
```if (model != null) { some code } else { code in case model is null }```

<@U5FS92HHS> when you start using kotlin it can be very tempting to use `let` and `?:` for cases where `if`/`else` are much better fits

i noticed this with myself and most people i've introduced to the language

Also there is a slight difference between these two.
Using `let`: code in `run` will be executed if `model` is `null`or if `some code` in `let` will return `null`.

&gt; `some code` in `let` will return `null`
true, which make it even more confusing

if it really matters I prefer this:
```val someResult = if (model != null) { some code } else null
if (someResult == null) {
 //code in case model or result is null
}```

but usually try to separate checking for receiver nullability and expression result

I’m still on the “let for everything”-train :laughing:

Interesting! I’ve used `let` operator when data could have changed in runtime, and also compiler doesn’t allow to have an `if/else`, so that’d be a good idea IMO, use let operator when an `if/else` is not allowed.

I definitely agree with <@UKATVFMPW> on using `let` to wrap mutable variables. But it’s kind of unclear from the sample whether that’s happening.

&gt; to wrap Mutable variables
```val immutable = mutable```

I hate to have to instantiate a new variable just to do that..
```
someMutable?.let {
  //lock state and do work
}
/*now I don't have another thing hanging around representing old state*/
```

It's really depends on case, of course, but usually local variable just more readable and has less nesting