‘A percent sign appearing in text is a literal’

The message “A percent sign appearing in text is a literal” can be caused by code like:

xo_emit("cost: %d", cost);

This code should be replaced with code like:

xo_emit("{L:cost}: {:cost/%d}", cost);

This can be a bit surprising and could be a field that was not properly converted to a libxo-style format string.

‘Unknown long name for role/modifier’

The message “Unknown long name for role/modifier” can be caused by code like:

xo_emit("{,humanization:value}", value);

This code should be replaced with code like:

xo_emit("{,humanize:value}", value);

The hn-* modifiers (hn-decimal, hn-space, hn-1000) are only valid for fields with the {h:} modifier.

‘Last character before field definition is a field type’

The message “Last character before field definition is a field type” can be caused by code like: A common typo:

xo_emit("{T:Min} T{:Max}");

This code should be replaced with code like:

xo_emit("{T:Min} {T:Max}");

Twiddling the “{” and the field role is a common typo.

‘Encoding format uses different number of arguments’

The message “Encoding format uses different number of arguments” can be caused by code like:

xo_emit("{:name/%6.6s %%04d/%s}", name, number);

This code should be replaced with code like:

xo_emit("{:name/%6.6s %04d/%s-%d}", name, number);

Both format should consume the same number of arguments off the stack

‘Only one field role can be used’

The message “Only one field role can be used” can be caused by code like:

xo_emit("{LT:Max}");

This code should be replaced with code like:

xo_emit("{T:Max}");

‘Potential missing slash after C, D, N, L, or T with format’

The message “Potential missing slash after C, D, N, L, or T with format” can be caused by code like:

xo_emit("{T:%6.6s}\n", "Max");

This code should be replaced with code like:

xo_emit("{T:/%6.6s}\n", "Max");

The “%6.6s” will be a literal, not a field format. While it’s possibly valid, it’s likely a missing “/”.

‘An encoding format cannot be given (roles: DNLT)’

The message “An encoding format cannot be given (roles: DNLT)” can be caused by code like:

xo_emit("{T:Max//%s}", "Max");

Fields with the C, D, N, L, and T roles are not emitted in the ‘encoding’ style (JSON, XML), so an encoding format would make no sense.

‘Format cannot be given when content is present (roles: CDLN)’

The message “Format cannot be given when content is present (roles: CDLN)” can be caused by code like:

xo_emit("{N:Max/%6.6s}", "Max");

Fields with the C, D, L, or N roles can’t have both static literal content (“{L:Label}”) and a format (“{L:/%s}”). This error will also occur when the content has a backslash in it, like “{N:Type of I/O}”; backslashes should be escaped, like “{N:Type of I\/O}”. Note the double backslash, one for handling ‘C’ strings, and one for libxo.

‘Field has color without fg- or bg- (role: C)’

The message “Field has color without fg- or bg- (role: C)” can be caused by code like:

xo_emit("{C:green}{:foo}{C:}", x);

This code should be replaced with code like:

xo_emit("{C:fg-green}{:foo}{C:}", x);

Colors must be prefixed by either “fg-” or “bg-“.

‘Field has invalid color or effect (role: C)’

The message “Field has invalid color or effect (role: C)” can be caused by code like:

xo_emit("{C:fg-purple,bold}{:foo}{C:gween}", x);

This code should be replaced with code like:

xo_emit("{C:fg-red,bold}{:foo}{C:fg-green}", x);

The list of colors and effects are limited. The set of colors includes default, black, red, green, yellow, blue, magenta, cyan, and white, which must be prefixed by either “fg-” or “bg-”. Effects are limited to bold, no-bold, underline, no-underline, inverse, no-inverse, normal, and reset. Values must be separated by commas.

‘Field has humanize modifier but no format string’

The message “Field has humanize modifier but no format string” can be caused by code like:

xo_emit("{h:value}", value);

This code should be replaced with code like:

xo_emit("{h:value/%d}", value);

Humanization is only value for numbers, which are not likely to use the default format (“%s”).

‘Field has hn-* modifier but not ‘h’ modifier’

The message “Field has hn-* modifier but not ‘h’ modifier” can be caused by code like:

xo_emit("{,hn-1000:value}", value);

This code should be replaced with code like:

xo_emit("{h,hn-1000:value}", value);

The hn-* modifiers (hn-decimal, hn-space, hn-1000) are only valid for fields with the {h:} modifier.

‘Value field must have a name (as content)”)’

The message “Value field must have a name (as content)”)” can be caused by code like:

xo_emit("{:/%s}", "value");

This code should be replaced with code like:

xo_emit("{:tag-name/%s}", "value");

The field name is used for XML and JSON encodings. These tags names are static and must appear directly in the field descriptor.

‘Use hyphens, not underscores, for value field name’

The message “Use hyphens, not underscores, for value field name” can be caused by code like:

xo_emit("{:no_under_scores}", "bad");

This code should be replaced with code like:

xo_emit("{:no-under-scores}", "bad");

Use of hyphens is traditional in XML, and the XOF_UNDERSCORES flag can be used to generate underscores in JSON, if desired. But the raw field name should use hyphens.

‘Value field name cannot start with digit’

The message “Value field name cannot start with digit” can be caused by code like:

xo_emit("{:10-gig/}");

This code should be replaced with code like:

xo_emit("{:ten-gig/}");

XML element names cannot start with a digit.

‘Value field name should be lower case’

The message “Value field name should be lower case” can be caused by code like:

xo_emit("{:WHY-ARE-YOU-SHOUTING}", "NO REASON");

This code should be replaced with code like:

xo_emit("{:why-are-you-shouting}", "no reason");

Lower case is more civilized. Even TLAs should be lower case to avoid scenarios where the differences between “XPath” and “Xpath” drive your users crazy. Lower case rules the seas.

‘Value field name should be longer than two characters’

The message “Value field name should be longer than two characters” can be caused by code like:

xo_emit("{:x}", "mumble");

This code should be replaced with code like:

xo_emit("{:something-meaningful}", "mumble");

Field names should be descriptive, and it’s hard to be descriptive in less than two characters. Consider your users and try to make something more useful. Note that this error often occurs when the field type is placed after the colon (“{:T/%20s}”), instead of before it (“{T:/20s}”).

‘Value field name contains invalid character’

The message “Value field name contains invalid character” can be caused by code like:

xo_emit("{:cost-in-$$/%u}", 15);

This code should be replaced with code like:

xo_emit("{:cost-in-dollars/%u}", 15);

An invalid character is often a sign of a typo, like “{:]}” instead of “{]:}”. Field names are restricted to lower-case characters, digits, and hyphens.

‘decoration field contains invalid character’

The message “decoration field contains invalid character” can be caused by code like:

xo_emit("{D:not good}");

This code should be replaced with code like:

xo_emit("{D:((}{:good}{D:))}", "yes");

This is minor, but fields should use proper roles. Decoration fields are meant to hold punctuation and other characters used to decorate the content, typically to make it more readable to human readers.

‘Anchor content should be decimal width’

The message “Anchor content should be decimal width” can be caused by code like:

xo_emit("{[:mumble}");

This code should be replaced with code like:

xo_emit("{[:32}");

Anchors need an integer value to specify the width of the set of anchored fields. The value can be positive (for left padding/right justification) or negative (for right padding/left justification) and can appear in either the start or stop anchor field descriptor.

‘Anchor format should be “%d”’

The message “Anchor format should be “%d”” can be caused by code like:

xo_emit("{[:/%s}");

This code should be replaced with code like:

xo_emit("{[:/%d}");

Anchors only grok integer values, and if the value is not static, if must be in an ‘int’ argument, represented by the “%d” format. Anything else is an error.

‘Anchor cannot have both format and encoding format”)’

The message “Anchor cannot have both format and encoding format”)” can be caused by code like:

xo_emit("{[:32/%d}");

This code should be replaced with code like:

xo_emit("{[:32}");

Anchors can have a static value or argument for the width, but cannot have both.

‘Max width only valid for strings’

The message “Max width only valid for strings” can be caused by code like:

xo_emit("{:tag/%2.4.6d}", 55);

This code should be replaced with code like:

xo_emit("{:tag/%2.6d}", 55);

libxo allows a true ‘max width’ in addition to the traditional printf-style ‘max number of bytes to use for input’. But this is supported only for string values, since it makes no sense for non-strings. This error may occur from a typo, like “{:tag/%6..6d}” where only one period should be used.