Pine version 3 migration guide

This document helps to migrate Pine Script code from @version=2 to @version=3.

Default behaviour of security function has changed

Let’s look at the simple security function use case. Add this indicator on an intraday chart:

This indicator is calculated based on historical data and looks somewhat into the future. At the first bar of every session an indicator plots the high price of the entire day. This could be useful in some cases for analysis, but doesn’t work for backtesting strategies.

We worked on this and made changes in Pine version 3. If this indicator is compiled with //@version=3 directive, we get a completely different picture:

The old behaviour is still available though. We added a parameter to the security function (the fifth one) called lookahead.

It can take on the form of two different values: barmerge.lookahead_off (and this is the default for Pine version 3) or barmerge.lookahead_on (which is the default for Pine version 2).

Self-referenced variables are removed

Pine version 2 pieces of code, containing a self-referencing variable:

Compiling this piece of code with Pine version 3 will give you an Undeclared identifier 's' error. It should be rewritten as:

s is now a mutable variable that is initialized at line 3. At line 3 the initial value gives the Pine compiler the information about the variable type. It’s a float in this example.

In some cases you may initialize that mutable variable (like s) with a na value. But in complex cases that won’t work.

Forward-referenced variables are removed

In this example f is a forward-referencing variable, because it’s referenced at line 3 before it was declared and initialized. In Pine version 3 this will give you an error Undeclared identifier 'f'. This example should be rewritten in Pine version 3 as follows:

Resolving a problem with a mutable variable in a security expression

When you migrate script to version 3 it’s possible that after removing self-referencing and forward-referencing variables the Pine compiler will give you an error:

Cannot use mutable variable as an argument for security function!

This limitation exists since mutable variables were introduced in Pine, i.e., in version 2. It can be resolved as before: wrap the code with a mutable variable in a function:

Math operations with booleans are forbidden

In Pine Script v2 there were rules of implicit conversion of booleans into numeric types. In v3 this is forbidden. There is a conversion of numeric types into booleans instead (0 and na values are false, all the other numbers are true). Example (In v2 this code compiles fine):

Variables s, s1 and s2 are of bool type. But at line 6 we add three of them and store the result in a variable sum. sum is a number, since we cannot add booleans. Booleans were implicitly converted to numbers (true values to 1.0 and false to 0.0) and then they were added.

This approach leads to unintentional errors in more complicated scripts. That’s why we no longer allow implicit conversion of booleans to numbers.

If you try to compile this example as a Pine v3 code, you’ll get an error: Cannot call `operator +` with arguments (series__bool, series__bool); <...> It means that you cannot use the addition operator with boolean values. To make this example work in Pine v3 you can do the following:

Function bton (abbreviation of boolean-to-number) explicitly converts any boolean value to a number if you really need this.