How to create an Expr that evaluates to Expr in Julia?
I have a variable ex that represents an Expr, I want to have a function exprwrap that creates an Expr from it which when evaluated is equal to ex.
Currently I implement it as follows:
ex = :(my + expr)
"Make an expression that when evaled returns the input ex."
function exprwrap(ex::Expr)
ret = :(:(du + mmy))
ret.args[1] = ex
ret
end
eval(exprwrap(ex)) == ex
Keep in mind that my and expr are not defined so :(:($$ex)) does not do the job.
What is a cleaner way to do this?
julia-lang metaprogramming
asked Nov 20 at 21:24
keorn
132
add a comment |
I have a variable ex that represents an Expr, I want to have a function exprwrap that creates an Expr from it which when evaluated is equal to ex.
Currently I implement it as follows:
ex = :(my + expr)
"Make an expression that when evaled returns the input ex."
function exprwrap(ex::Expr)
ret = :(:(du + mmy))
ret.args[1] = ex
ret
end
eval(exprwrap(ex)) == ex
Keep in mind that my and expr are not defined so :(:($$ex)) does not do the job.
What is a cleaner way to do this?
julia-lang metaprogramming
asked Nov 20 at 21:24
keorn
132
add a comment |
I have a variable ex that represents an Expr, I want to have a function exprwrap that creates an Expr from it which when evaluated is equal to ex.
Currently I implement it as follows:
ex = :(my + expr)
"Make an expression that when evaled returns the input ex."
function exprwrap(ex::Expr)
ret = :(:(du + mmy))
ret.args[1] = ex
ret
end
eval(exprwrap(ex)) == ex
Keep in mind that my and expr are not defined so :(:($$ex)) does not do the job.
What is a cleaner way to do this?
julia-lang metaprogramming
asked Nov 20 at 21:24
keorn
132
I have a variable ex that represents an Expr, I want to have a function exprwrap that creates an Expr from it which when evaluated is equal to ex.
Currently I implement it as follows:
ex = :(my + expr)
"Make an expression that when evaled returns the input ex."
function exprwrap(ex::Expr)
ret = :(:(du + mmy))
ret.args[1] = ex
ret
end
eval(exprwrap(ex)) == ex
Keep in mind that my and expr are not defined so :(:($$ex)) does not do the job.
What is a cleaner way to do this?
julia-lang metaprogramming
julia-lang metaprogramming
asked Nov 20 at 21:24
keorn
132
asked Nov 20 at 21:24
keorn
132
asked Nov 20 at 21:24
keorn
132
asked Nov 20 at 21:24
keorn
132
asked Nov 20 at 21:24
keorn
132
132
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
You can write:
Expr(:quote, x)
or
Expr(:block, ex)
or
:($ex;)
Additionally you could do:
Meta.parse(":($ex)")
which is not simple but shows you how Julia parses ex when it appears in the source code and you can see that it is the same as Expr(:quote, ex).
Similarly yo can check that Meta.parse("($ex;)") == Expr(:block, ex).
answered Nov 20 at 21:37
Bogumił Kamiński
11.8k11120
2
There is alsoMeta.quotwhich is evaluates toExpr(:quote, x)too.
– 张实唯
Nov 23 at 2:28
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53401757%2fhow-to-create-an-expr-that-evaluates-to-expr-in-julia%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
You can write:
Expr(:quote, x)
or
Expr(:block, ex)
or
:($ex;)
Additionally you could do:
Meta.parse(":($ex)")
which is not simple but shows you how Julia parses ex when it appears in the source code and you can see that it is the same as Expr(:quote, ex).
Similarly yo can check that Meta.parse("($ex;)") == Expr(:block, ex).
answered Nov 20 at 21:37
Bogumił Kamiński
11.8k11120
2
There is alsoMeta.quotwhich is evaluates toExpr(:quote, x)too.
– 张实唯
Nov 23 at 2:28
add a comment |
You can write:
Expr(:quote, x)
or
Expr(:block, ex)
or
:($ex;)
Additionally you could do:
Meta.parse(":($ex)")
which is not simple but shows you how Julia parses ex when it appears in the source code and you can see that it is the same as Expr(:quote, ex).
Similarly yo can check that Meta.parse("($ex;)") == Expr(:block, ex).
answered Nov 20 at 21:37
Bogumił Kamiński
11.8k11120
2
There is alsoMeta.quotwhich is evaluates toExpr(:quote, x)too.
– 张实唯
Nov 23 at 2:28
add a comment |
You can write:
Expr(:quote, x)
or
Expr(:block, ex)
or
:($ex;)
Additionally you could do:
Meta.parse(":($ex)")
which is not simple but shows you how Julia parses ex when it appears in the source code and you can see that it is the same as Expr(:quote, ex).
Similarly yo can check that Meta.parse("($ex;)") == Expr(:block, ex).
answered Nov 20 at 21:37
Bogumił Kamiński
11.8k11120
You can write:
Expr(:quote, x)
or
Expr(:block, ex)
or
:($ex;)
Additionally you could do:
Meta.parse(":($ex)")
which is not simple but shows you how Julia parses ex when it appears in the source code and you can see that it is the same as Expr(:quote, ex).
Similarly yo can check that Meta.parse("($ex;)") == Expr(:block, ex).
answered Nov 20 at 21:37
Bogumił Kamiński
11.8k11120
edited Nov 20 at 21:51
answered Nov 20 at 21:37
Bogumił Kamiński
11.8k11120
answered Nov 20 at 21:37
Bogumił Kamiński
11.8k11120
answered Nov 20 at 21:37
Bogumił Kamiński
11.8k11120
11.8k11120
2
There is alsoMeta.quotwhich is evaluates toExpr(:quote, x)too.
– 张实唯
Nov 23 at 2:28
add a comment |
2
There is alsoMeta.quotwhich is evaluates toExpr(:quote, x)too.
– 张实唯
Nov 23 at 2:28
2
2
There is also
Meta.quot which is evaluates to Expr(:quote, x) too.– 张实唯
Nov 23 at 2:28
There is also
Meta.quot which is evaluates to Expr(:quote, x) too.– 张实唯
Nov 23 at 2:28
add a comment |
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Some of your past answers have not been well-received, and you're in danger of being blocked from answering.
Please pay close attention to the following guidance:
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53401757%2fhow-to-create-an-expr-that-evaluates-to-expr-in-julia%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
