# Number lines on code blocks

The `hook_numberLines` function automates line numbering on code blocks.

    library(chunkhooks)
    hook_numberLines()

# Basic usage

By default, the feature affects only source codes.

    # By default, Source lines are numbered
    "Output lines are not numbered"

    ## [1] "Output lines are not numbered"

The feature can be introduced to other types of code blocks as well, i.e. output, message, warning, and error.

    hook_numberLines(c("source", "output"))

    # After `hook_numberLines(c("source", "output"))`,
    # Source lines are numbered
    "Output lines are also numbered"

    ## [1] "Output lines are also numbered"

In order to disable the feature on selected chunks, specify the `numberLines` chunk option that determines which types of code blocks need line numbers.

    # numberLines="output" is specified as a chunk option
    # Source lines are not numbered
    "Output lines are also numbered"

    ## [1] "Output lines are also numbered"