golang cannot be on the left

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Golang is an efficient, concise, easy to learn and use programming language. It originated as an internal Google project to improve the productivity and compilation speed of existing languages. Since Golang was first released in 2009, it has become one of the most popular languages ​​for web and cloud application development. However, among all Golang's advantages, there is one that may seem less intuitive: the way assignments lag behind other programming languages.

In most programming languages, we can place a variable on the left and assign it a new value. For example, we can write in C language like this: a = 1;. Similarly, in Python, we can write: a=1. This is called assignment with lvalues ​​and rvalues. A common practice is to place lvalues ​​(variables) to the left of the equal sign and rvalues ​​(results of calculations or data) to the right of the equal sign. However, Golang seems unable to do this.

In Golang, we cannot place variables on the left. For the following code:

a := 1
a = 2

This is a good example showing this constraint. The first line assigns an integer value 1 to the variable a, which is a shorthand form. The second line attempts to overwrite the value of a with the value 2, but is not allowed to assign a to the left of the equal sign. If you do this, you will receive a warning from the compiler or a direct compilation error.

So, why can’t Golang use this form of assignment? Is it really necessary that variables cannot be placed on the left? This is a question worth exploring.

In fact, this assignment method does cause some logical problems. For example, suppose we have the following code:

a := 1
b := 2
a = b = 3

In other languages, we can replace a and b Set to 3 respectively. However, in Golang this produces a compilation error. Because the return value of the assignment operation is a bool type, not an lvalue, this nested assignment does not work. In this case we have to write like this:

a := 1
b := 2
b = 3
a = b

This also keeps the logic clear and easy to read.

In addition, in some cases, not allowing lvalue assignment can also increase program robustness. Consider the following code snippet:

a, b := 1, 2
if a = b; a == 2 {

// do something

}

This code Meaning, if a equals b and the value of a is 2, then do some operation. If lvalue assignment is allowed in Golang, the above code will be interpreted by the compiler as if b == 2 { ... }, because in this case, a is assigned to b itself, not 2. This can cause logic errors and make the program brittle and unstable.

Finally, although Golang cannot assign on the left, there are many other ways to accomplish the same operation. For example, we can declare a new variable and assign it to the original variable. Alternatively, we can use compound assignment operators such as increment assignment (=) or decrement assignment (-=). These methods ensure code readability and ease of maintenance.

In general, although Golang cannot assign values ​​on the left side, this is a reasonable decision. This constraint ensures that the code is clearer, easier to read, easier to maintain, and increases the robustness of the program. Therefore, it makes sense for any Golang developer to understand this limitation and not try to circumvent it.

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