Merge 460473a87f into b492a9d765

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
 For a steady stream of TILs, [sign up for my newsletter](https://crafty-builder-6996.ck.page/e169c61186).
 
-_1508 TILs and counting..._
+_1510 TILs and counting..._
 
 ---
 
@@ -888,6 +888,7 @@ _1508 TILs and counting..._
 - [Access Instance Variables](python/access-instance-variables.md)
 - [Create A Dummy DataFrame In Pandas](python/create-a-dummy-dataframe-in-pandas.md)
 - [Dunder Methods](python/dunder-methods.md)
+- [Override The Boolean Context Of A Class](python/override-the-boolean-context-of-a-class.md)
 - [Store And Access Immutable Data In A Tuple](python/store-and-access-immutable-data-in-a-tuple.md)
 - [Test A Function With Pytest](python/test-a-function-with-pytest.md)
 - [Use pipx To Install End User Apps](python/use-pipx-to-install-end-user-apps.md)
@@ -1221,6 +1222,7 @@ _1508 TILs and counting..._
 - [Find The Min And Max With A Single Call](ruby/find-the-min-and-max-with-a-single-call.md)
 - [Finding The Source of Ruby Methods](ruby/finding-the-source-of-ruby-methods.md)
 - [Format A Hash Into A String Template](ruby/format-a-hash-into-a-string-template.md)
+- [Forward All Arguments To Another Method](ruby/forward-all-arguments-to-another-method.md)
 - [Generate A Signed JWT Token](ruby/generate-a-signed-jwt-token.md)
 - [Generate Ruby Version And Gemset Files With RVM](ruby/generate-ruby-version-and-gemset-files-with-rvm.md)
 - [Get Info About Your RubyGems Environment](ruby/get-info-about-your-ruby-gems-environment.md)

javascript/immutable-remove-with-the-spread-operator.md

@@ -15,10 +15,8 @@ const remove = (items,index) => {
 };
 
 const list = [1,2,3,4,5];
-remove(list, 2);
-// [1,2,3,4]
-list
-// [1,2,3,4,5]
+remove(list, 2); // [1,2,4,5]
+// list still [1,2,3,4,5]
 ```
 
 It only took a couple lines of code and immutability is baked in.

python/override-the-boolean-context-of-a-class.md

@@ -0,0 +1,86 @@
+# Override The Boolean Context Of A Class
+
+Everything in Python has a truthiness that can be checked with `bool()`. An
+empty list (`[]`) is falsy. A non-empty list (`[1,2,3]`) is truthy. Similar
+with numbers:
+
+```python
+>>> bool(0)
+False
+>>> bool(1)
+True
+```
+
+Any instance of an object is going to be truthy by default. If you want to
+control in what context an instance is considered truthy or falsy, you can
+override
+[`__bool__()`](https://docs.python.org/3/reference/datamodel.html#object.__bool__).
+If that's not implemented, but
+[`__len__()`](https://docs.python.org/3/reference/datamodel.html#object.__len__)
+is, then it will fallback to that.
+
+Let's look at a few example classes:
+
+```python
+class CartZero:
+    def __init__(self, items=[]):
+        self.items = items or []
+
+class CartBool:
+    def __init__(self, items=[]):
+        self.items = items or []
+
+    def __bool__(self):
+        print("__bool__() override")
+        return bool(self.items)
+
+class CartLen:
+    def __init__(self, items=[]):
+        self.items = items or []
+
+    def __len__(self):
+        print("__len__() override")
+        return len(self.items)
+
+class CartBoolAndLen:
+    def __init__(self, items=[]):
+        self.items = items or []
+
+    def __len__(self):
+        print("__len__() override")
+        return len(self.items)
+
+    def __bool__(self):
+        print("__bool__() override")
+        return bool(self.items)
+
+cart1 = CartZero()
+cart2 = CartBool()
+cart3 = CartLen()
+cart4 = CartBoolAndLen()
+
+print("CartZero() -> %s" %(bool(cart1)))
+print('')
+print("CartBool() -> %s" %(bool(cart2)))
+print('')
+print("CartLen() -> %s" %(bool(cart3)))
+print('')
+print("CartBoolAndLen() -> %s" %(bool(cart4)))
+```
+
+An 'empty' `Cart` be default is truthy. However, we can override some
+combination of `__bool__()` or `__len__()` to give it a boolean context that
+goes `false` when "empty".
+
+```
+CartZero() -> True
+
+__bool__() override
+CartBool() -> False
+
+__len__() override
+CartLen() -> False
+
+__bool__() override
+CartBoolAndLen() -> False
+```

ruby/forward-all-arguments-to-another-method.md

@@ -0,0 +1,45 @@
+# Forward All Arguments To Another Method
+
+There are three types of arguments that a Ruby method can receive. Positional
+arguments, keyword arguments, and a block argument.
+
+A method that deals with all three might be defined like this:
+
+```ruby
+def forwarding_method(*args, **kwargs, &block)
+  # implementation
+end
+```
+
+Now lets say we have some concrete method that we want to forward these
+arguments to:
+
+```ruby
+def concrete_method(*args, **kwargs)
+  x = args.first || 1
+  key, y = kwargs.first || [:a, 2]
+
+  puts "Dealing with #{x} and key #{key}: #{y}"
+
+  yield(x, y)
+end
+```
+
+We could forward arguments the longhand way like this:
+
+```ruby
+def forwarding_method(*args, **kwargs, &block)
+  concrete_method(*args, **kwargs, &block)
+end
+```
+
+However, since Ruby 2.7 we have access to a shorthand "triple-dot" syntax for
+forwarding all arguments.
+
+```ruby
+def forwarding_method(...)
+  concrete_method(...)
+end
+```
+
+[source](https://ruby-doc.org/3.3.6/syntax/methods_rdoc.html#label-Argument+Forwarding)