Allow addition of custom objects #2309
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| @@ -60,46 +60,88 @@ add_ggplot <- function(p, object, objectname) { | |||
| if (is.null(object)) return(p) | |||
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This can now be a method of the generic
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Oh - Didn’t knew you could dispatch on NULL
R/plot-construction.r
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| #' a ggplot with [+.gg]. | ||
| #' | ||
| #' @param object An object to add to the plot | ||
| #' @param p The ggplot object to add `object` to |
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I think plot and object_name would be better argument names
| ggplot_add.test_object <- function(object, p, objectname) { | ||
| 10 | ||
| } | ||
| test_that("Methods can be defined for adding custom objects", { |
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You can define the method inside the test, just to make things slightly cleaner.
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For some reason I’m having problems getting dispatch to work correctly in the test. Moving it out fixed it locally but it still throws an error on travis..?
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Do you have any idea why methods defined inside test_that expressions are not being dispatched to?
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Yes, it's something to do with the weird way in which S3 dispatch happens. I forget all the details, but just move it outside for now.
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Does |
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I have some strange ( |
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OK - I'm up to speed again. No It doesn't pass locally. The test method won't get dispatched to when called as part of Check, but works fine when pasted into the console. I guess the problem is the same - that S3 methods are not properly registered when defined within tests... No idea how to properly test this then... |
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I think you can just drop the test - if the S3 dispatch was failing, every plot would break. |
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I never thought I should live to hear you ask me to remove a test - this will haunt you 😛 |
# Conflicts: # NEWS.md Merge branch 'tidyverse/master' into custom-object-add # Conflicts: # NEWS.md
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Thanks! |
As discussed. This PR adds the possibility of developers writing custom behaviour for adding other objects than those defined by ggplot2 to a gg object.
It works by falling back to the
add_to_ggplot()generic inadd_ggplot(). A potential change to the PR would be to writeadd_to_ggplot()methods for all the build in classes as well thus completely removing the if else check fromadd_ggplot()