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In some programming languages, an assignment statement returns a value, while in others it does not. In most expression-oriented programming languages (for example, C), the assignment statement returns the assigned value, allowing such idioms as x = y = a, in which the assignment statement y = a returns the value of a, which is then assigned to x.
Python features sequence unpacking where multiple expressions, each evaluating to anything that can be assigned (to a variable, writable property, etc.) are associated in an identical manner to that forming tuple literals—and, as a whole, are put on the left-hand side of the equal sign in an assignment statement.
A notable example of this is Python, where = is not an operator, but rather just a separator in the assignment statement. Although Python allows multiple assignments as each assignment were an expression, this is simply a special case of the assignment statement built into the language grammar rather than a true expression.
Python sets are very much like mathematical sets, and support operations like set intersection and union. Python also features a frozenset class for immutable sets, see Collection types. Dictionaries (class dict) are mutable mappings tying keys and corresponding values. Python has special syntax to create dictionaries ({key: value})
Likewise, a syntactic construct like an if-condition-then statement may be denoted by means of a single node with three branches. This distinguishes abstract syntax trees from concrete syntax trees, traditionally designated parse trees. Parse trees are typically built by a parser during the source code translation and compiling process.
Augmented assignment (or compound assignment) is the name given to certain assignment operators in certain programming languages (especially those derived from C).An augmented assignment is generally used to replace a statement where an operator takes a variable as one of its arguments and then assigns the result back to the same variable.
Some languages (PL/I, Fortran 95, and later) allow a statement label at the start of a for-loop that can be matched by the compiler against the same text on the corresponding end-loop statement. Fortran also allows the EXIT and CYCLE statements to name this text; in a nest of loops, this makes clear which loop is intended. However, in these ...
For example, to pass conditionally different values as an argument for a constructor of a field or a base class, it is impossible to use a plain if-else statement; in this case we can use a conditional assignment expression, or a function call. Bear in mind also that some types allow initialization, but do not allow assignment, or even that the ...