ctxt_stack() can be tricky to use in real code because all
intervening frames are returned with the stack, including those at
ctxt_stack() own call site. stack_trim() makes it easy to
remove layers of intervening calls.
stack_trim(stack, n = 1)
Arguments
| stack | An evaluation stack. |
|---|---|
| n | The number of call frames (not eval frames) to trim off the top of the stack. In other words, the number of layers of intervening frames to trim. |
Life cycle
These functions are deprecated and replaced by trace_back().
Examples
#> [[1]] #> <frame 35> (33) #> expr: identity(ctxt_stack()) #> env: [local 0xa7b6310] #> #> [[2]] #> <frame 34> (33) #> expr: identity(identity(ctxt_stack())) #> env: [local 0xa7b61f8] #> #> [[3]] #> <frame 33> (32) #> expr: eval(expr, envir, enclos) #> env: [local 0x8b16b60] #> #> [[4]] #> <frame 32> (22) #> expr: eval(expr, envir, enclos) #> env: [local 0xa7b6038] #> #> [[5]] #> <frame 31> (22) #> expr: withVisible(eval(expr, envir, enclos)) #> env: [local 0xa7b5e08] #> #> [[6]] #> <frame 30> (22) #> expr: withCallingHandlers(withVisible(eval(expr, envir, enclos)), warning = wHandler, <...> #> env: [local 0xa7b5778] #> #> [[7]] #> <frame 29> (28) #> expr: doTryCatch(return(expr), name, parentenv, handler) #> env: [local 0xa7b5190] #> #> [[8]] #> <frame 28> (27) #> expr: tryCatchOne(expr, names, parentenv, handlers[[1L]]) #> env: [local 0xa7b4e48] #> #> [[9]] #> <frame 27> (26) #> expr: tryCatchList(expr, classes, parentenv, handlers) #> env: [local 0xa7b4b00] #> #> [[10]] #> <frame 26> (25) #> expr: tryCatch(expr, error = function(e) { <...> #> env: [local 0xa7c3d28] #> #> [[11]] #> <frame 25> (24) #> expr: try(f, silent = TRUE) #> env: [local 0xa7c3af8] #> #> [[12]] #> <frame 24> (22) #> expr: handle(ev <- withCallingHandlers(withVisible(eval(expr, envir, <...> #> env: [local 0xa7c3970] #> #> [[13]] #> <frame 23> (22) #> expr: timing_fn(handle(ev <- withCallingHandlers(withVisible(eval(expr, <...> #> env: [local 0xa7c3890] #> #> [[14]] #> <frame 22> (21) #> expr: evaluate_call(expr, parsed$src[[i]], envir = envir, enclos = enclos, <...> #> env: [frame 0xa815920] #> #> [[15]] #> <frame 21> (20) #> expr: evaluate::evaluate(x, child_env(env), new_device = TRUE) #> env: [frame 0xaa76b30] #> #> [[16]] #> <frame 20> (19) #> expr: highlight_examples(code, topic, env = env) #> env: [frame 0xaa6ee40] #> #> [[17]] #> <frame 19> (18) #> expr: run_examples(tags$tag_examples[[1]], env = new.env(parent = globalenv()), <...> #> env: [frame 0xaa4ffc0] #> #> [[18]] #> <frame 18> (17) #> expr: data_reference_topic(topic, pkg, examples = examples, run_dont_run = run_dont_run) #> env: [frame 0xa7a6e10] #> #> [[19]] #> <frame 17> (16) #> expr: .f(.x[[i]], ...) #> env: [frame 0xa866260] #> #> [[20]] #> <frame 16> (15) #> expr: purrr::map(topics, build_reference_topic, pkg = pkg, lazy = lazy, <...> #> env: [frame 0x4609728] #> #> [[21]] #> <frame 15> (14) #> expr: build_reference(pkg, lazy = lazy, examples = examples, run_dont_run = run_dont_run, <...> #> env: [frame 0x47728c0] #> #> [[22]] #> <frame 14> (13) #> expr: build_site_local(pkg = pkg, examples = examples, run_dont_run = run_dont_run, <...> #> env: [frame 0x47bbb28] #> #> [[23]] #> <frame 13> (12) #> expr: pkgdown::build_site(...) #> env: [frame 0x47b2060] #> #> [[24]] #> <frame 12> (0) #> expr: (function (..., crayon_enabled, crayon_colors, pkgdown_internet) <...> #> env: [frame 0x446b1c8] #> #> [[25]] #> <frame 11> (0) #> expr: (function (what, args, quote = FALSE, envir = parent.frame()) <...> #> env: [frame 0x4f05758] #> #> [[26]] #> <frame 10> (0) #> expr: do.call(do.call, c(readRDS("/tmp/RtmpDApnXm/file4ee732ebd9b8"), <...> #> env: [frame 0x4466470] #> #> [[27]] #> <frame 9> (0) #> expr: saveRDS(do.call(do.call, c(readRDS("/tmp/RtmpDApnXm/file4ee732ebd9b8"), <...> #> env: [frame 0x44667f0] #> #> [[28]] #> <frame 8> (0) #> expr: withCallingHandlers({ <...> #> env: [frame 0x4461538] #> #> [[29]] #> <frame 7> (6) #> expr: doTryCatch(return(expr), name, parentenv, handler) #> env: [frame 0x445dd98] #> #> [[30]] #> <frame 6> (5) #> expr: tryCatchOne(expr, names, parentenv, handlers[[1L]]) #> env: [frame 0x445e0e0] #> #> [[31]] #> <frame 5> (2) #> expr: tryCatchList(expr, names[-nh], parentenv, handlers[-nh]) #> env: [frame 0x445e498] #> #> [[32]] #> <frame 4> (3) #> expr: doTryCatch(return(expr), name, parentenv, handler) #> env: [frame 0x445ea48] #> #> [[33]] #> <frame 3> (2) #> expr: tryCatchOne(tryCatchList(expr, names[-nh], parentenv, handlers[-nh]), <...> #> env: [frame 0x445ed90] #> #> [[34]] #> <frame 2> (1) #> expr: tryCatchList(expr, classes, parentenv, handlers) #> env: [frame 0x445f0d8] #> #> [[35]] #> <frame 1> (0) #> expr: tryCatch(withCallingHandlers({ <...> #> env: [frame 0x445f810] #> #> [[36]] #> <frame 0> [global] #> expr: NULL #> env: [global] #> #> attr(,"class") #> [1] "ctxt_stack" "stack"#> [[1]] #> <frame 33> (32) #> expr: eval(expr, envir, enclos) #> env: [local 0x8b16b60] #> #> [[2]] #> <frame 32> (22) #> expr: eval(expr, envir, enclos) #> env: [local 0x7767eb0] #> #> [[3]] #> <frame 31> (22) #> expr: withVisible(eval(expr, envir, enclos)) #> env: [local 0x7767c80] #> #> [[4]] #> <frame 30> (22) #> expr: withCallingHandlers(withVisible(eval(expr, envir, enclos)), warning = wHandler, <...> #> env: [local 0x776b3e8] #> #> [[5]] #> <frame 29> (28) #> expr: doTryCatch(return(expr), name, parentenv, handler) #> env: [local 0x776ae70] #> #> [[6]] #> <frame 28> (27) #> expr: tryCatchOne(expr, names, parentenv, handlers[[1L]]) #> env: [local 0x776ab28] #> #> [[7]] #> <frame 27> (26) #> expr: tryCatchList(expr, classes, parentenv, handlers) #> env: [local 0x776a690] #> #> [[8]] #> <frame 26> (25) #> expr: tryCatch(expr, error = function(e) { <...> #> env: [local 0x776cd20] #> #> [[9]] #> <frame 25> (24) #> expr: try(f, silent = TRUE) #> env: [local 0x776caf0] #> #> [[10]] #> <frame 24> (22) #> expr: handle(ev <- withCallingHandlers(withVisible(eval(expr, envir, <...> #> env: [local 0x776c968] #> #> [[11]] #> <frame 23> (22) #> expr: timing_fn(handle(ev <- withCallingHandlers(withVisible(eval(expr, <...> #> env: [local 0x776c888] #> #> [[12]] #> <frame 22> (21) #> expr: evaluate_call(expr, parsed$src[[i]], envir = envir, enclos = enclos, <...> #> env: [frame 0x77b3740] #> #> [[13]] #> <frame 21> (20) #> expr: evaluate::evaluate(x, child_env(env), new_device = TRUE) #> env: [frame 0xaa76b30] #> #> [[14]] #> <frame 20> (19) #> expr: highlight_examples(code, topic, env = env) #> env: [frame 0xaa6ee40] #> #> [[15]] #> <frame 19> (18) #> expr: run_examples(tags$tag_examples[[1]], env = new.env(parent = globalenv()), <...> #> env: [frame 0xaa4ffc0] #> #> [[16]] #> <frame 18> (17) #> expr: data_reference_topic(topic, pkg, examples = examples, run_dont_run = run_dont_run) #> env: [frame 0xa7a6e10] #> #> [[17]] #> <frame 17> (16) #> expr: .f(.x[[i]], ...) #> env: [frame 0xa866260] #> #> [[18]] #> <frame 16> (15) #> expr: purrr::map(topics, build_reference_topic, pkg = pkg, lazy = lazy, <...> #> env: [frame 0x4609728] #> #> [[19]] #> <frame 15> (14) #> expr: build_reference(pkg, lazy = lazy, examples = examples, run_dont_run = run_dont_run, <...> #> env: [frame 0x47728c0] #> #> [[20]] #> <frame 14> (13) #> expr: build_site_local(pkg = pkg, examples = examples, run_dont_run = run_dont_run, <...> #> env: [frame 0x47bbb28] #> #> [[21]] #> <frame 13> (12) #> expr: pkgdown::build_site(...) #> env: [frame 0x47b2060] #> #> [[22]] #> <frame 12> (0) #> expr: (function (..., crayon_enabled, crayon_colors, pkgdown_internet) <...> #> env: [frame 0x446b1c8] #> #> [[23]] #> <frame 11> (0) #> expr: (function (what, args, quote = FALSE, envir = parent.frame()) <...> #> env: [frame 0x4f05758] #> #> [[24]] #> <frame 10> (0) #> expr: do.call(do.call, c(readRDS("/tmp/RtmpDApnXm/file4ee732ebd9b8"), <...> #> env: [frame 0x4466470] #> #> [[25]] #> <frame 9> (0) #> expr: saveRDS(do.call(do.call, c(readRDS("/tmp/RtmpDApnXm/file4ee732ebd9b8"), <...> #> env: [frame 0x44667f0] #> #> [[26]] #> <frame 8> (0) #> expr: withCallingHandlers({ <...> #> env: [frame 0x4461538] #> #> [[27]] #> <frame 7> (6) #> expr: doTryCatch(return(expr), name, parentenv, handler) #> env: [frame 0x445dd98] #> #> [[28]] #> <frame 6> (5) #> expr: tryCatchOne(expr, names, parentenv, handlers[[1L]]) #> env: [frame 0x445e0e0] #> #> [[29]] #> <frame 5> (2) #> expr: tryCatchList(expr, names[-nh], parentenv, handlers[-nh]) #> env: [frame 0x445e498] #> #> [[30]] #> <frame 4> (3) #> expr: doTryCatch(return(expr), name, parentenv, handler) #> env: [frame 0x445ea48] #> #> [[31]] #> <frame 3> (2) #> expr: tryCatchOne(tryCatchList(expr, names[-nh], parentenv, handlers[-nh]), <...> #> env: [frame 0x445ed90] #> #> [[32]] #> <frame 2> (1) #> expr: tryCatchList(expr, classes, parentenv, handlers) #> env: [frame 0x445f0d8] #> #> [[33]] #> <frame 1> (0) #> expr: tryCatch(withCallingHandlers({ <...> #> env: [frame 0x445f810] #> #> [[34]] #> <frame 0> [global] #> expr: NULL #> env: [global] #> #> attr(,"class") #> [1] "ctxt_stack" "stack"# Note that it also takes care of calls intervening at its own call # site: identity(identity( stack_trim(identity(identity(ctxt_stack()))) ))#> [[1]] #> <frame 33> (32) #> expr: eval(expr, envir, enclos) #> env: [local 0x8b16b60] #> #> [[2]] #> <frame 32> (22) #> expr: eval(expr, envir, enclos) #> env: [local 0x6c581d8] #> #> [[3]] #> <frame 31> (22) #> expr: withVisible(eval(expr, envir, enclos)) #> env: [local 0x6c57d78] #> #> [[4]] #> <frame 30> (22) #> expr: withCallingHandlers(withVisible(eval(expr, envir, enclos)), warning = wHandler, <...> #> env: [local 0x6c57330] #> #> [[5]] #> <frame 29> (28) #> expr: doTryCatch(return(expr), name, parentenv, handler) #> env: [local 0x6c56920] #> #> [[6]] #> <frame 28> (27) #> expr: tryCatchOne(expr, names, parentenv, handlers[[1L]]) #> env: [local 0x6c565a0] #> #> [[7]] #> <frame 27> (26) #> expr: tryCatchList(expr, classes, parentenv, handlers) #> env: [local 0x6c5ca28] #> #> [[8]] #> <frame 26> (25) #> expr: tryCatch(expr, error = function(e) { <...> #> env: [local 0x6c5bc98] #> #> [[9]] #> <frame 25> (24) #> expr: try(f, silent = TRUE) #> env: [local 0x6c61ce8] #> #> [[10]] #> <frame 24> (22) #> expr: handle(ev <- withCallingHandlers(withVisible(eval(expr, envir, <...> #> env: [local 0x6c61230] #> #> [[11]] #> <frame 23> (22) #> expr: timing_fn(handle(ev <- withCallingHandlers(withVisible(eval(expr, <...> #> env: [local 0x6c61150] #> #> [[12]] #> <frame 22> (21) #> expr: evaluate_call(expr, parsed$src[[i]], envir = envir, enclos = enclos, <...> #> env: [frame 0x6c94ea0] #> #> [[13]] #> <frame 21> (20) #> expr: evaluate::evaluate(x, child_env(env), new_device = TRUE) #> env: [frame 0xaa76b30] #> #> [[14]] #> <frame 20> (19) #> expr: highlight_examples(code, topic, env = env) #> env: [frame 0xaa6ee40] #> #> [[15]] #> <frame 19> (18) #> expr: run_examples(tags$tag_examples[[1]], env = new.env(parent = globalenv()), <...> #> env: [frame 0xaa4ffc0] #> #> [[16]] #> <frame 18> (17) #> expr: data_reference_topic(topic, pkg, examples = examples, run_dont_run = run_dont_run) #> env: [frame 0xa7a6e10] #> #> [[17]] #> <frame 17> (16) #> expr: .f(.x[[i]], ...) #> env: [frame 0xa866260] #> #> [[18]] #> <frame 16> (15) #> expr: purrr::map(topics, build_reference_topic, pkg = pkg, lazy = lazy, <...> #> env: [frame 0x4609728] #> #> [[19]] #> <frame 15> (14) #> expr: build_reference(pkg, lazy = lazy, examples = examples, run_dont_run = run_dont_run, <...> #> env: [frame 0x47728c0] #> #> [[20]] #> <frame 14> (13) #> expr: build_site_local(pkg = pkg, examples = examples, run_dont_run = run_dont_run, <...> #> env: [frame 0x47bbb28] #> #> [[21]] #> <frame 13> (12) #> expr: pkgdown::build_site(...) #> env: [frame 0x47b2060] #> #> [[22]] #> <frame 12> (0) #> expr: (function (..., crayon_enabled, crayon_colors, pkgdown_internet) <...> #> env: [frame 0x446b1c8] #> #> [[23]] #> <frame 11> (0) #> expr: (function (what, args, quote = FALSE, envir = parent.frame()) <...> #> env: [frame 0x4f05758] #> #> [[24]] #> <frame 10> (0) #> expr: do.call(do.call, c(readRDS("/tmp/RtmpDApnXm/file4ee732ebd9b8"), <...> #> env: [frame 0x4466470] #> #> [[25]] #> <frame 9> (0) #> expr: saveRDS(do.call(do.call, c(readRDS("/tmp/RtmpDApnXm/file4ee732ebd9b8"), <...> #> env: [frame 0x44667f0] #> #> [[26]] #> <frame 8> (0) #> expr: withCallingHandlers({ <...> #> env: [frame 0x4461538] #> #> [[27]] #> <frame 7> (6) #> expr: doTryCatch(return(expr), name, parentenv, handler) #> env: [frame 0x445dd98] #> #> [[28]] #> <frame 6> (5) #> expr: tryCatchOne(expr, names, parentenv, handlers[[1L]]) #> env: [frame 0x445e0e0] #> #> [[29]] #> <frame 5> (2) #> expr: tryCatchList(expr, names[-nh], parentenv, handlers[-nh]) #> env: [frame 0x445e498] #> #> [[30]] #> <frame 4> (3) #> expr: doTryCatch(return(expr), name, parentenv, handler) #> env: [frame 0x445ea48] #> #> [[31]] #> <frame 3> (2) #> expr: tryCatchOne(tryCatchList(expr, names[-nh], parentenv, handlers[-nh]), <...> #> env: [frame 0x445ed90] #> #> [[32]] #> <frame 2> (1) #> expr: tryCatchList(expr, classes, parentenv, handlers) #> env: [frame 0x445f0d8] #> #> [[33]] #> <frame 1> (0) #> expr: tryCatch(withCallingHandlers({ <...> #> env: [frame 0x445f810] #> #> [[34]] #> <frame 0> [global] #> expr: NULL #> env: [global] #> #> attr(,"class") #> [1] "ctxt_stack" "stack"# It is especially useful when used within a function that needs to # inspect the evaluation stack but should nonetheless be callable # within nested calls without side effects: stack_util <- function() { # n = 2 means that two layers of intervening calls should be # removed: The layer at ctxt_stack()'s call site (including the # stack_trim() call), and the layer at stack_util()'s call. stack <- stack_trim(ctxt_stack(), n = 2) stack } user_fn <- function() { # A user calls your stack utility with intervening frames: identity(identity(stack_util())) } # These intervening frames won't appear in the evaluation stack identity(user_fn())#> [[1]] #> <frame 35> (33) #> expr: user_fn() #> env: [local 0x5f8d168] #> #> [[2]] #> <frame 34> (33) #> expr: identity(user_fn()) #> env: [local 0x5f8d0f8] #> #> [[3]] #> <frame 33> (32) #> expr: eval(expr, envir, enclos) #> env: [local 0x8b16b60] #> #> [[4]] #> <frame 32> (22) #> expr: eval(expr, envir, enclos) #> env: [local 0x5f8cf38] #> #> [[5]] #> <frame 31> (22) #> expr: withVisible(eval(expr, envir, enclos)) #> env: [local 0x5f8cd08] #> #> [[6]] #> <frame 30> (22) #> expr: withCallingHandlers(withVisible(eval(expr, envir, enclos)), warning = wHandler, <...> #> env: [local 0x5f8c678] #> #> [[7]] #> <frame 29> (28) #> expr: doTryCatch(return(expr), name, parentenv, handler) #> env: [local 0x5f8e3a0] #> #> [[8]] #> <frame 28> (27) #> expr: tryCatchOne(expr, names, parentenv, handlers[[1L]]) #> env: [local 0x5f93a60] #> #> [[9]] #> <frame 27> (26) #> expr: tryCatchList(expr, classes, parentenv, handlers) #> env: [local 0x5f933d0] #> #> [[10]] #> <frame 26> (25) #> expr: tryCatch(expr, error = function(e) { <...> #> env: [local 0x5f92640] #> #> [[11]] #> <frame 25> (24) #> expr: try(f, silent = TRUE) #> env: [local 0x5f921e0] #> #> [[12]] #> <frame 24> (22) #> expr: handle(ev <- withCallingHandlers(withVisible(eval(expr, envir, <...> #> env: [local 0x5f97c20] #> #> [[13]] #> <frame 23> (22) #> expr: timing_fn(handle(ev <- withCallingHandlers(withVisible(eval(expr, <...> #> env: [local 0x5f97a60] #> #> [[14]] #> <frame 22> (21) #> expr: evaluate_call(expr, parsed$src[[i]], envir = envir, enclos = enclos, <...> #> env: [frame 0x5fdf3c0] #> #> [[15]] #> <frame 21> (20) #> expr: evaluate::evaluate(x, child_env(env), new_device = TRUE) #> env: [frame 0xaa76b30] #> #> [[16]] #> <frame 20> (19) #> expr: highlight_examples(code, topic, env = env) #> env: [frame 0xaa6ee40] #> #> [[17]] #> <frame 19> (18) #> expr: run_examples(tags$tag_examples[[1]], env = new.env(parent = globalenv()), <...> #> env: [frame 0xaa4ffc0] #> #> [[18]] #> <frame 18> (17) #> expr: data_reference_topic(topic, pkg, examples = examples, run_dont_run = run_dont_run) #> env: [frame 0xa7a6e10] #> #> [[19]] #> <frame 17> (16) #> expr: .f(.x[[i]], ...) #> env: [frame 0xa866260] #> #> [[20]] #> <frame 16> (15) #> expr: purrr::map(topics, build_reference_topic, pkg = pkg, lazy = lazy, <...> #> env: [frame 0x4609728] #> #> [[21]] #> <frame 15> (14) #> expr: build_reference(pkg, lazy = lazy, examples = examples, run_dont_run = run_dont_run, <...> #> env: [frame 0x47728c0] #> #> [[22]] #> <frame 14> (13) #> expr: build_site_local(pkg = pkg, examples = examples, run_dont_run = run_dont_run, <...> #> env: [frame 0x47bbb28] #> #> [[23]] #> <frame 13> (12) #> expr: pkgdown::build_site(...) #> env: [frame 0x47b2060] #> #> [[24]] #> <frame 12> (0) #> expr: (function (..., crayon_enabled, crayon_colors, pkgdown_internet) <...> #> env: [frame 0x446b1c8] #> #> [[25]] #> <frame 11> (0) #> expr: (function (what, args, quote = FALSE, envir = parent.frame()) <...> #> env: [frame 0x4f05758] #> #> [[26]] #> <frame 10> (0) #> expr: do.call(do.call, c(readRDS("/tmp/RtmpDApnXm/file4ee732ebd9b8"), <...> #> env: [frame 0x4466470] #> #> [[27]] #> <frame 9> (0) #> expr: saveRDS(do.call(do.call, c(readRDS("/tmp/RtmpDApnXm/file4ee732ebd9b8"), <...> #> env: [frame 0x44667f0] #> #> [[28]] #> <frame 8> (0) #> expr: withCallingHandlers({ <...> #> env: [frame 0x4461538] #> #> [[29]] #> <frame 7> (6) #> expr: doTryCatch(return(expr), name, parentenv, handler) #> env: [frame 0x445dd98] #> #> [[30]] #> <frame 6> (5) #> expr: tryCatchOne(expr, names, parentenv, handlers[[1L]]) #> env: [frame 0x445e0e0] #> #> [[31]] #> <frame 5> (2) #> expr: tryCatchList(expr, names[-nh], parentenv, handlers[-nh]) #> env: [frame 0x445e498] #> #> [[32]] #> <frame 4> (3) #> expr: doTryCatch(return(expr), name, parentenv, handler) #> env: [frame 0x445ea48] #> #> [[33]] #> <frame 3> (2) #> expr: tryCatchOne(tryCatchList(expr, names[-nh], parentenv, handlers[-nh]), <...> #> env: [frame 0x445ed90] #> #> [[34]] #> <frame 2> (1) #> expr: tryCatchList(expr, classes, parentenv, handlers) #> env: [frame 0x445f0d8] #> #> [[35]] #> <frame 1> (0) #> expr: tryCatch(withCallingHandlers({ <...> #> env: [frame 0x445f810] #> #> [[36]] #> <frame 0> [global] #> expr: NULL #> env: [global] #> #> attr(,"class") #> [1] "ctxt_stack" "stack"