Show eldoc in minibuffer when point is inside function arguments list (ESS R mode)

[ywwry66]

Hi there, I am a first time lsp-mode user. After a quick setup with ESS R mode, I am very happy with the result. However, there is one thing I am missing from the original R mode, that is, whenever cursor/point is inside the arguments list of any function, eldoc documentation will show in the minibuffer. Now with lsp-mode, I get the documentation when I type a function name followed by ( (like a trigger char), but it is no longer triggered by cursor position. I've tried lsp-signature-auto-activate but with no luck. Am I missing something here? Thanks for your help!

[yyoncho]

There are two methods in lsp protocol:

textDocument/hover - this method is wired to eldoc and M-x lsp-describe-thing-at-point
textDocument/signatureHelp - this is what you see when you press the signatureTriggerChar, you can manually trigger it via C-S-SPC. If you install posframe package it will pop up in a frame.

[ywwry66]

Thanks for the detail explanation, which is really helpful. Since you mentioned lsp-describe-thing-at-point, I have a followup question. In the *lsp-help* buffer triggered by lsp-describe-thing-at-point, I see some raw html code not rendered correctly, while in the original ess-r-mode, there is no rendering issue. Do you think this is something to be fixed on lsp-mode's end, or a bug from the languageserver R package?

[yyoncho]

@ywwry66 I need screeshot(s) + the log from the client/server communication.

[ywwry66]

I am not sure what kind of log you want. Below is copied from the *lsp-log* buffer:

Command "R --slave -e languageserver::run()" is present on the path.
Command "R --slave -e languageserver::run()" is present on the path.
Found the following clients for /Users/ruiyangwu/test/test.R: (server-id lsp-r, priority 0)
The following clients were selected based on priority: (server-id lsp-r, priority 0)

Here is a screenshot

[ywwry66]

Hi @yyoncho, I was able to get the following verbose log using lsp-toggle-trace-io.

[Trace - 05:38:19 PM] Sending request 'textDocument/codeAction - (16)'.
Params: {
  "textDocument": {
    "uri": "file:///Users/ruiyangwu/test/test.R"
  },
  "range": {
    "start": {
      "line": 0,
      "character": 0
    },
    "end": {
      "line": 0,
      "character": 0
    }
  },
  "context": {
    "diagnostics": []
  }
}


[Trace - 05:38:19 PM] Sending request 'textDocument/documentLink - (17)'.
Params: {
  "textDocument": {
    "uri": "file:///Users/ruiyangwu/test/test.R"
  }
}


[Trace - 05:38:19 PM] Received response 'textDocument/codeAction - (16)' in 21ms.
Result: []


[Trace - 05:38:19 PM] Received response 'textDocument/documentLink - (17)' in 47ms.
Result: null


[Trace - 05:38:21 PM] Sending request 'textDocument/hover - (18)'.
Params: {
  "textDocument": {
    "uri": "file:///Users/ruiyangwu/test/test.R"
  },
  "position": {
    "line": 1,
    "character": 0
  }
}


[Trace - 05:38:21 PM] Sending request 'textDocument/codeAction - (19)'.
Params: {
  "textDocument": {
    "uri": "file:///Users/ruiyangwu/test/test.R"
  },
  "range": {
    "start": {
      "line": 1,
      "character": 0
    },
    "end": {
      "line": 1,
      "character": 0
    }
  },
  "context": {
    "diagnostics": []
  }
}


[Trace - 05:38:21 PM] Sending request 'textDocument/documentLink - (20)'.
Params: {
  "textDocument": {
    "uri": "file:///Users/ruiyangwu/test/test.R"
  }
}


[Trace - 05:38:21 PM] Sending request 'textDocument/documentHighlight - (21)'.
Params: {
  "textDocument": {
    "uri": "file:///Users/ruiyangwu/test/test.R"
  },
  "position": {
    "line": 1,
    "character": 0
  }
}


[Trace - 05:38:21 PM] Received response 'textDocument/hover - (18)' in 245ms.
Result: {
  "contents": "<div class=\"container\">\n\n**length** *{base}*\n\nLength of an Object\n\n------------------------------------------------------------------------\n\n### Description\n\nGet or set the length of vectors (including lists) and factors, and of\nany other\n<span style=\"font-family: Courier New, Courier; color: #666666;\">**R**</span>\nobject for which a method has been defined.\n\n### Usage\n\n``` R\nlength(x)\nlength(x) <- value\n```\n\n### Arguments\n\n|         |                                                                                                                               |\n|---------|-------------------------------------------------------------------------------------------------------------------------------|\n| `x`     | an <span style=\"font-family: Courier New, Courier; color: #666666;\">**R**</span> object. For replacement, a vector or factor. |\n| `value` | a non-negative integer or double (which will be rounded down).                                                                |\n\n### Details\n\nBoth functions are generic: you can write methods to handle specific\nclasses of objects, see InternalMethods. `length<-` has a `\"factor\"`\nmethod.\n\nThe replacement form can be used to reset the length of a vector. If a\nvector is shortened, extra values are discarded and when a vector is\nlengthened, it is padded out to its new length with `NA`s (`nul` for raw\nvectors).\n\nBoth are primitive functions.\n\n### Value\n\nThe default method for `length` currently returns a non-negative\n`integer` of length 1, except for vectors of more than `2^{31}-1`\nelements, when it returns a double.\n\nFor vectors (including lists) and factors the length is the number of\nelements. For an environment it is the number of objects in the\nenvironment, and `NULL` has length 0. For expressions and pairlists\n(including language objects and dotlists) it is the length of the\npairlist chain. All other objects (including functions) have length one:\nnote that for functions this differs from S.\n\nThe replacement form removes all the attributes of `x` except its names,\nwhich are adjusted (and if necessary extended by `\"\"`).\n\n### Warning\n\nPackage authors have written methods that return a result of length\nother than one\n([<span class=\"pkg\">Formula</span>](https://CRAN.R-project.org/package=Formula))\nand that return a vector of type `double`\n([<span class=\"pkg\">Matrix</span>](https://CRAN.R-project.org/package=Matrix)),\neven with non-integer values (earlier versions of\n[<span class=\"pkg\">sets</span>](https://CRAN.R-project.org/package=sets)).\nWhere a single double value is returned that can be represented as an\ninteger it is returned as a length-one integer vector.\n\n### References\n\nBecker, R. A., Chambers, J. M. and Wilks, A. R. (1988) *The New S\nLanguage*. Wadsworth & Brooks/Cole.\n\n### See Also\n\n`nchar` for counting the number of characters in character vectors,\n`lengths` for getting the length of every element in a list.\n\n### Examples\n\n``` R\nlength(diag(4))  # = 16 (4 x 4)\nlength(options())  # 12 or more\nlength(y ~ x1 + x2 + x3)  # 3\nlength(expression(x, {y <- x^2; y+2}, x^y))  # 3\n\n## from example(warpbreaks)\nrequire(stats)\n\nfm1 <- lm(breaks ~ wool * tension, data = warpbreaks)\nlength(fm1$call)      # 3, lm() and two arguments.\nlength(formula(fm1))  # 3, ~ lhs rhs\n```\n\n------------------------------------------------------------------------\n\n<div style=\"text-align: center;\">\n\n\\[Package *base* version 4.2.3 \\]\n\n</div>\n\n</div>",
  "range": {
    "start": {
      "line": 1,
      "character": 0
    },
    "end": {
      "line": 1,
      "character": 6
    }
  }
}


[Trace - 05:38:21 PM] Received response 'textDocument/codeAction - (19)' in 256ms.
Result: []


[Trace - 05:38:21 PM] Received response 'textDocument/documentLink - (20)' in 281ms.
Result: null


[Trace - 05:38:21 PM] Received response 'textDocument/documentHighlight - (21)' in 326ms.
Result: [
  {
    "range": {
      "start": {
        "line": 1,
        "character": 0
      },
      "end": {
        "line": 1,
        "character": 6
      }
    },
    "kind": 1
  }
]


[Trace - 05:38:27 PM] Sending request 'textDocument/hover - (22)'.
Params: {
  "textDocument": {
    "uri": "file:///Users/ruiyangwu/test/test.R"
  },
  "position": {
    "line": 1,
    "character": 0
  }
}


[Trace - 05:38:27 PM] Received response 'textDocument/hover - (22)' in 75ms.
Result: {
  "contents": "<div class=\"container\">\n\n**length** *{base}*\n\nLength of an Object\n\n------------------------------------------------------------------------\n\n### Description\n\nGet or set the length of vectors (including lists) and factors, and of\nany other\n<span style=\"font-family: Courier New, Courier; color: #666666;\">**R**</span>\nobject for which a method has been defined.\n\n### Usage\n\n``` R\nlength(x)\nlength(x) <- value\n```\n\n### Arguments\n\n|         |                                                                                                                               |\n|---------|-------------------------------------------------------------------------------------------------------------------------------|\n| `x`     | an <span style=\"font-family: Courier New, Courier; color: #666666;\">**R**</span> object. For replacement, a vector or factor. |\n| `value` | a non-negative integer or double (which will be rounded down).                                                                |\n\n### Details\n\nBoth functions are generic: you can write methods to handle specific\nclasses of objects, see InternalMethods. `length<-` has a `\"factor\"`\nmethod.\n\nThe replacement form can be used to reset the length of a vector. If a\nvector is shortened, extra values are discarded and when a vector is\nlengthened, it is padded out to its new length with `NA`s (`nul` for raw\nvectors).\n\nBoth are primitive functions.\n\n### Value\n\nThe default method for `length` currently returns a non-negative\n`integer` of length 1, except for vectors of more than `2^{31}-1`\nelements, when it returns a double.\n\nFor vectors (including lists) and factors the length is the number of\nelements. For an environment it is the number of objects in the\nenvironment, and `NULL` has length 0. For expressions and pairlists\n(including language objects and dotlists) it is the length of the\npairlist chain. All other objects (including functions) have length one:\nnote that for functions this differs from S.\n\nThe replacement form removes all the attributes of `x` except its names,\nwhich are adjusted (and if necessary extended by `\"\"`).\n\n### Warning\n\nPackage authors have written methods that return a result of length\nother than one\n([<span class=\"pkg\">Formula</span>](https://CRAN.R-project.org/package=Formula))\nand that return a vector of type `double`\n([<span class=\"pkg\">Matrix</span>](https://CRAN.R-project.org/package=Matrix)),\neven with non-integer values (earlier versions of\n[<span class=\"pkg\">sets</span>](https://CRAN.R-project.org/package=sets)).\nWhere a single double value is returned that can be represented as an\ninteger it is returned as a length-one integer vector.\n\n### References\n\nBecker, R. A., Chambers, J. M. and Wilks, A. R. (1988) *The New S\nLanguage*. Wadsworth & Brooks/Cole.\n\n### See Also\n\n`nchar` for counting the number of characters in character vectors,\n`lengths` for getting the length of every element in a list.\n\n### Examples\n\n``` R\nlength(diag(4))  # = 16 (4 x 4)\nlength(options())  # 12 or more\nlength(y ~ x1 + x2 + x3)  # 3\nlength(expression(x, {y <- x^2; y+2}, x^y))  # 3\n\n## from example(warpbreaks)\nrequire(stats)\n\nfm1 <- lm(breaks ~ wool * tension, data = warpbreaks)\nlength(fm1$call)      # 3, lm() and two arguments.\nlength(formula(fm1))  # 3, ~ lhs rhs\n```\n\n------------------------------------------------------------------------\n\n<div style=\"text-align: center;\">\n\n\\[Package *base* version 4.2.3 \\]\n\n</div>\n\n</div>",
  "range": {
    "start": {
      "line": 1,
      "character": 0
    },
    "end": {
      "line": 1,
      "character": 6
    }
  }
}


[Trace - 05:38:28 PM] Sending request 'textDocument/codeAction - (23)'.
Params: {
  "textDocument": {
    "uri": "file:///Users/ruiyangwu/test/test.R"
  },
  "range": {
    "start": {
      "line": 1,
      "character": 0
    },
    "end": {
      "line": 1,
      "character": 0
    }
  },
  "context": {
    "diagnostics": []
  }
}


[Trace - 05:38:28 PM] Sending request 'textDocument/documentLink - (24)'.
Params: {
  "textDocument": {
    "uri": "file:///Users/ruiyangwu/test/test.R"
  }
}


[Trace - 05:38:28 PM] Received response 'textDocument/codeAction - (23)' in 62ms.
Result: []


[Trace - 05:38:28 PM] Received response 'textDocument/documentLink - (24)' in 91ms.
Result: null

[ywwry66]

After some testing I can confirm this is actually a bug from the languageserver R package. Thanks for the help!